While there are a lot of complications in determining who wins if factoring the “height” of their power. For the sake of just an entirely fun game of speculation and fussing over lore, the state of each factions power is relatively following the start of BFA. In addition because Void Elves and High Elves are considered part of the same “faction” in the same way as Highborne and Night Elves are.
So in a four way scrap for the seat of the world—who wins?
vs tusk elves*
If we’re taking their power individually as nations, without any allied support, I think I’d say Blood Elves, right now.
The Void Elves are a people in exile who can barely be considered a government at this point. Their main land claim is a few tents on the ruins of a desolate void world.
The Nightborne and Night Elves have been left reeling from current events. The Nightborne had a full on Civil War which undoubtedly depleted both their resources and their population. The Nightborne lost a lot of people to the withered, and quite a lot sided with Elisande and became Felborne too. Their society is constrained to a single city, and it’s one that’s damaged by war. An entire district was wiped out by the Legion, after all. And a lot of the ruling class had to be overthrown to usurp Elisande. I think they’re still focusing on restructuring their society and certainly aren’t in a position to claim global elven hegemony.
The Night Elves are in a similar situation, due to Teldrassil. They lost the heartland of their nation, and everyone on it. They’re at Hyjal now but their resources were undoubtedly spent quite heavily trying to reconquer Darkshore. They’ve had a tough time of it, and aren’t ready.
The Blood Elves have also experienced loss… but aside from the exodus of the void elves their society has actually been quite stable for several years. They are firmly in control of Eversong Woods (though admittedly they no longer have the population to settle the Ghostlands, and thus mostly control the main roads and little else.) The Blood Knight Order is going strong, and combined with the Farstriders, it has meant that Quel’thalas has a diverse and stable military. Add to this technological innovation - use of Blood Golems for instance, following Throne of Thunder, has added more to the Blood Elven strength. They have troops enough to spare to support the reoccupation of Orgrimmar, and these troops patrol the city as we speak.
In short, the Blood Elves, while suffering great loss from the height of Quel’thalassian power, are the most stable and growing elven nation at the present time. If it came to war between the four powers - there’s no doubt in my mind that the Blood Elves would win.
All this said there’s no chance any elven power has the means to dominate the world. They’re all vastly weakened in one way or another, and somewhat dependant on their allies.
Ok, now. For a proper answer.
Prior to BfA, this would’ve been the Night Elves in a landslide. Even if they had been in decline for ages, they still more or less owned Kalimdor. This stands to reason they had a nice chunky population to go with it, as well as organization to defend it against the threats they had previously faced (which, at this time, was old god servants and the Legion, so not precisely push overs).
Post-BfA, however, makes this a tad more difficult. The tragedy the Night Elves suffered at the hands of the Horde has effectively put them in the same position the Blood Elves were post-Arthas (right down to humans being literally no help!).
Velves/Healves, for the most part, wouldn’t be a huge contender in this regard, either. As Sarestha said, their full presence is effectively minimal compared to those they’d be competing with. Super good at espionage and magic? Damn right. Staying power required to contend? Not so much.
Funny enough, it’s the Horde elves who, relatively speaking, are in the overall better geopolitical position. While the Nightborne did suffer a civil war and having to be under demonic thumbs for a bit, they are rather insulated from threats thanks to the Highmountain Tauren sharing the continent with them and Zandalar sharing the waters closest to them. The bigger issue for them, however, is the fact they’re a city state. Position to punch above their weight? Yes, position to become a major power? Not so much…
Blood Elves are the fun ones. In game, we were introduced to them still in their low point. Still recovering, still in pain and still needing to use dire measures to preserve their people. This said, unlike the Night Elves and Nightborne, they have actually had the needed time to recover, begin recouping and stabilize themselves. While still not what they once were, Quel’thalas is a major power on Azeroth and has demonstrated it is fully able to wage entire military campaigns when they feel it is needed. On top of that, they are shown to have a governing body who has their head on their shoulders and military leaders who can carry their duties out well. This can also be added to the fact they are functionally the Horde’s magic backbone, enough so they can prevent the Alliance, a faction with tons of magic based races, from securing dominance in that field (and that alone is saying a lot.)
no one because the elves team up together and unite their terrible ideas to just completely destroy azeroth once and for all
the nelves could be at peak power and would lose
why?
wow writers don’t give the nelves victories.
Idk the Night Elves basically saved the world in Warcraft 3 whereas the orcs just got partially corrupted again, the humans destroyed their own kingdom (Thanks Arthas) and the undead were just the bad guys.
Honestly? Night elves.
The Kaldorei were dealt a terrible blow in the War of Thorns. The Horde’s blitzkrieg through Ashenvale and Darkshore was brutal, as was the burning of Teldrassil, but the speed at which their army progressed through elven territory did not give them sufficient time to hunt down fleeing noncombatants or establish fortresses to hold the land. Hyjal, Moonglade, and Winterspring were largely left untouched, as were strongholds in Feralas. The night elves continental population was at risk, but for the most part did not suffer catastrophic losses. One can argue that previous conflicts have done much to deplete their military might. However, they have not shouldered that burden alone; everyone on Azeroth has endured a near constant state of warfare.
Even at their lowest, the Kaldorei are still in better shape to assert control of whatever they choose than the runner up: blood elves. The Sin’dorei have benefitted immensely from their alliance with the Horde. Aside from a few inconveniences, they have been left unmolested in their small corner of the Eastern Kingdoms, granting plenty of time to stabilize their losses during the Third War. However, they are in no position to support protracted, large-scale, military engagements by virtue of it being only eight years since they faced near extinction. Not just the scourging of Quel’Thalas, but the schism in Outland and expected contributions to following Horde campaigns have mitigated their recovery. Sin’dorei are no doubt in better condition than they were joining the Horde, but are a pale shadow of what they were before Arthas cut a path through their kingdom.
Nightborne follow behind blood elves thanks to the Burning Legion’s occupation - which quickly turned into extermination - and millennia of enforced stagnation to support what they believed were the world’s only surviving elves. Even if they remained untouched by the Legion’s incursion, their entire population was sequestered within a bubble that encompassed little more than a - surprisingly dense - city and neighboring countryside. Exile was literally a drawn-out execution thanks to their dependence on the Nightwell. They had little political power to exert before rejoining the modern world, and what existed was soon gutted by the Legion.
Void elves are borderline inconsequential.
Edit:
And out of left field comes the naga with a steel chair!
Even in their current situation, I’d say the Night Elves come out on top. It took a full on invasion of the combined Horde military just to take Ashenvale/Darkshore, and they payed heavily in terms of casualties to do it. Then the Night Elves, after having lost Teldrassil and with next to no support from the greater Alliance, were able to reverse all those gains and push the occupying forces Horde back out in a matter of months/a year.
Night Elves just suffer badly under the Worf effect.
Blood Elves were already 90% wiped out before Garithos got to them prior to WoW. They’re more or less only capable of holding onto Silvermoon City and the surrounding countryside by themselves. And that’s before another number split off with the Void Elves.
Nightborne similarly seem restricted to Surumar and the surrounding territory. On the other hand, outside of the sudden and disatrous Legion invasion/occupation, their forces hadn’t seen battle in a while.
Frankly, why the Elves don’t just band together and form their own faction escapes my pondering.
High Elves -> suffered loss of their population in a tragic event at the hand of a human (empowered by unnatural forces) -> forced to seek out a new source of power to avenge their fallen -> became Blood Elves.
Night Elves -> Suffered loss of their population in a tragic event at the hand of a “creation” of that same human. -> forced to seek out a new source of power to avenge their fallen. -> became Night Warriors.
Nightbourne -> Saw what happened to the Night Elves and shielded themselves -> their society then crumbled with the interference of demonic forces. -> When the nightborne sought help from the Alliance, they were denied. Hence, turning to the Horde.
Void elves -> playing with forces too dangerous for even Sylvanas, kicked out of the Horde. The Alliance shows no qualms about taking them in and carelessly lets them continue to play with those mind-controlling powers.
Why any elven race still allies to the Alliance escapes me. That’s three times the Alliance has failed elves.
I propose a new elf faction that looks out for their own. No one else seems to be doing them any good. 
Well, no, not strictly true at all. The Alliance (the high elves and night elves) explicitly helped, Tyrande was just mean to Thalyssra about it. Which for some reason is what they used to justify the Nightborne joining the Horde, instead of just building on the whole shared culture and history and views as the blood elves.
As far as which elf faction has the edge, I’d say narrowly blood elves. I don’t think they’re as well-off as some others do, given that they haven’t really been able to dedicate themselves to recovery since it’s just been war after war after war (see Sylvanas threatening Lor’themar to force them to send troops to Northrend when they could barely spare anyone after Quel’danas). With that said, blood elves were originally flavored as the most disciplined survivors of an entire race. The Blood Knights were and are able to challenge the Silver Hand, the Farstriders are some of the best rangers on Azeroth, and blood elven mages are typically pretty mighty. They’re also pretty unified (even with the blood knight/farstrider rivalry) because anyone who disagreed too much was banished (this is not a good thing morally, to be clear).
I’m not saying that the Night Elves are weak, though. The Sentinels are historically very good fighters and the Priestesses of Elune don’t really need much explanation (also I am struggling to come up with one). Druids are often neutral, but enough aren’t that I’d say they certainly give the night elves an edge there. The recent reintegration of the Highborne gives the Night Elves access to powerful arcane casters. If it weren’t for the recent Horde atrocities I’d say Night elves win easily. However, with Ashenvale, Darkshore, and Teldrassil essentially decimated and desecrated, they’re not in a great position. Couple that with a certain disunity between factions in the Night Elves (mounting tensions with the Alliance, not everyone is a Night Warrior, Maiev is both a high-ranking official and a serial killer of Highborne, many druids prefer napping to action), and I’d think that currently they’re a close second. Currently many are displaced even though in theory they could try resettling in Hyjal or other places. Give it a couple years and they’re in first again easily.
Makes me wonder what Blizz has in mind after we get back from the Shadowlands - knowing that they’ve confirmed that time moves differently between both realms.
Perhaps we’ll finally get that faction mix up (or even a third faction) we’ve been all theorizing?
And agree with all the previous posters. The Blood Elves have had time to re-establish themselves as a military power over the years. Yes, reduced drastically in number, but they’ve kept a sharp eye on re-building for several expansions now.
The night elves have suffered far too much. However, maybe we’ll see them re-bound back with the far-stretching narrative license that Blizz seems to take whenever they need to?
All should join team Yrel.
She has cookies and said that if we join her we get a spot on top of the pack on Azeroth.
Honestly, I’d say that it’d be a toss-up between Blood Elves or Night Elves currently. Void Elves and High Elves, as much as I like y’all, are just too much of a non-factor and wouldn’t necessarily stand a chance if a free-for-all happened. Nightborne I could see putting up a bit of a fight, but they’re still recovering from a civil war and 10,000 years of disconnection from the world as a whole.
The Blood Elves and Night Elves certainly are no where near as powerful as they both were prior to the Third War, but currently both factions would probably be contenders for the title of “Strongest Elves” due to their starting to recover from previous crises and setbacks.
This pretty much sums it up. I honestly think most of the individual factions currently within the Alliance and Horde (not just the Elves) have been weakened to such a point by recent events, that pretty much everyone is dependent on their allies in some form or another.
It feels like whenever Blizz introduces a new race to a faction, said race just went/is going through some tough sh*t, and needs allies to depend on. I know this doesn’t always happen, but I can think of quite a few recent examples. Just something that I thought of as a result of this convo 
I have this headcanon (completely unfounded) that the 8 classic core races are the most individually powerful militaries, with the 5 expansion races being slightly less powerful, and the allies races being the smallest.
So with that said, I would say Night Elf. Sure, they lost a lot of numbers in the latest incredibly written saga, but they’re all over the place man. Half of Kalimdor has their settlements and don’t forget how many are in Hyjal still.
I’m not so sure on that. Sure, void elves and Vulpera probably have no real military might, but despite their navies being in ruins Zandalar and Kul Tiras should have military power that rivals or exceeds any of the core races, and Dark Iron are probably similar.
You’re right, Zandalar and Kul Tirans are definitely a huge exception, they are probably the second most powerful under the Orcs and Stormwind Humans, I would guess.
None of the other Allied races strike me as very large populations though. Again, I have no evidence for this, it’s just my brain worms
Everyone knows that power depends on having a capital city that can be visited in game.
So, I know I was only joking about the whole tusk elves thing… but post-BfA is interestingly enough a good point to assess that.
So, I did do the whole thing for 4 elves meant for this thread, so general stance remains the same. Sindorei have a slight lead over the Nelves while the Nelves effectively blow the other two competitors out of the water.
So, Onto the tusk elves!
Functionally, if trolls were permitted entry to this based on them being tusk-elves by virtue of Blizzard’s evolution, they’d come out victorious. The reason? A few things I actually thought of when I was looking at the coming Ardenwald stuff.
While I understand a lot of people rightfully herald the tauren as the Horde’s champions of nature, a very strong case can be made for the Zandalari and Darkspear. Keep in mind, both groups of trolls have a fierce loyality to their Loa, most of the Loa are also Wild Gods (akin to the Night Elves, just without the Cenarius). Unlike the Tauren and Night Elves, however, the Loa are considerably more present in Zandalari society, to the point that the Loa flat out live -in the city and towns with them-. Add to that both sets of trolls have individuals skilled with the arcane and elements. As it stands, they’d be the only ones in this contest with access to Nature, Light, Elements, Arcane and Fel.
Now, to break down the portion which is probably most relevant. Zandalar still stands as a sovereign nation. While the Alliance was able to occupy Dazar’alor and murder Rastakhan, they still had to high tail it out five minutes later when the main army counter-attacked. Bear in mind, they needed to use deception to get a window. Actually sacking Dazar’alor wasn’t really on the table if you have to bolt from the counter-attack. In terms of logistics and organization, the Sindorei would no doubt match them. Unlike the Sindorei, however, the Zandalari can still keep the entirety of their capital populated and functioning, as well as the surrounding areas (and, given Farraki being used to settle Voldun with the Vulpera, quite likely the whole continent). Also, most importantly, all the internal issues were conviently cleaned out in BfA, all the way up to the leader who was too complacent.
The other break down. People give Blizz crap for the Night Elves only taking it on the chin. Lore wise, that only happened very recently with the orcs turning up on Kalimdor. Trolls have lore wise been taking it on the chin since the Night Elves went full manifest destiny and not only still exist in numerous regions, but apparently pose enough of a threat that the Alliance still takes them seriously, which likely means they have the numbers, if lacking the immediate organization.
End result of including the tusk elves? Nightborne, Velves, Nelves and Belves kneel before the Golden Throne. Mostly because while battered, Zandas in the Horde have left trolls poised to unify in a peaceful manner again and probably move forward. (and by peaceful, I mean Amani likely get the worst part of the deal)