Used to play both more or less evenly, but the new direction since (SL? I don’t know, I skipped that one) moving away from a faction story focus meant there was very little to gain by doing so.
If there’s only one side of the story, then there’s no call to play both. Saddly, my horde characters have yet to see much action in DF
Alliance. But I identify as Horde.
Feel like I’ve just about gone full circle. My first ever character was a draenei paladin. For years after that, all the way up until coming back for DF after a brief hiatus at the end of BfA - I’ve been Horde.
I don’t know why I’ve decided to go Alliance this go around, but I do think it’s in part that the Horde has so little story presence anymore.
As far as what I’ve been seeing more of; definitely Alliance. Even in WM, they generally outnumber the Horde players by a fair margin.
i find this to be a very common reason for people to swap to the Alliance, tbh. It was the motivation for me to make my original Alliance characters when I came back to WoW.
that, combined with the Horde being the full out, outright villains with our leaders doing indefensibly evil things during the last two major Faction War arcs.
but in the long run, I ended up back on the Horde side where I belong though. I just vibe better with the Horde, personally.
Can’t speak for the game at large but I love playing Horde because it’s Horde, ig lol. I just like the cities, lore figures and races more. Regardless tho I still play lots of Ally too. I keep a balanced amount of characters between the two factions on my two realms while eventually planning to hit the character cap. I don’t have a high-end gameplay mindset so I don’t really mind the racial ability differences. 
Honestly, Horde purely because most of my geared alts on Horde side. Knowing what I know now I’d have probably gone full Alliance. Still debating on either having two sets of alts for Alliance and Horde or mixing them together and having just 12 alts and one main (for the classes)
The two servers I have played most on (Frostmourne and before that Proudmore) are incredibly alliance heavy so I think I initially went with that. Now that it almost doesn’t matter anymore I roll races I like and almost forget they are factional. That said my 4 in the warband display at login are all alliance right now: void elf, mechagnome, human and lightforged draenei. That’s entirely accidental, I think.
Of my 34 toons, 11 of which are 80’s, around 90% are Horde
Most of my time on WoW has been horde but since BFA I’ve jumped up play time on Alliance characters, even on horde I mostly play my Night Borne. Alliance mostly still feels like the Alliance in vanilla but expanded. Horde feels less so and for me translates to a unsatisfying playing experience. Org is the in game representation of how Horde feels to play for me.
What kind of a question is that?
I never played in the Alliance.
Do you know more now or you’re getting old and your brain is melting like the scourge?? I see no reason to be in the Alliance at all.
Of course it is intentional makes no sense to ignore an entire faction in Tww, the only forsaken I saw was being eaten by spiders and was melted in the end by poison and they are even making the Nerubians look like Alliance.
Don’t we forget the destruction of the Horde’s Lore in BfA and Shadownlands, the equilibrium in numbers in the Horda was due to elves and now they decided to give the Alliance elves too. There is an strategy behind it.
I play both but I’ve always been an alliance main. Back in 2004 I wanted to roll horde, but all my friends picked alliance so I went with night elf druid (almost always played night elves in warcraft 3 anyways).
I still have my original night elf druid character, and he’s still technically my main, the one I always use first when returning to the game to see what’s changed. I was never very interested in other alliance races until much later on, eventually made an alliance pandaren mage and dark iron dwarf shaman. The shaman was deleted to make a vulpera shaman when they became available (used an orc hunter to unlock them), and the vulpera shaman has since been my horde side main.
Now I’m playing alliance dracthyr evoker primarily while waiting on new dracthyr classes.
I have played both sides since vanilla and I’ll probably always play both sides. I did make my night elf hunter look like Sylvanas, though. She’s pretty much the only alliance alt I really play frequently these days. Undead are too awesome for me to ever abandon them.
Mostly Alliance actually but since we apparently do not have active racial capitols anymore forcing everyone into the latest expansion town or Ogrimmar/Stormwind then, there we are. Personally, I want to spread out the player base with services everywhere. I want my bloodelves to use Silvermoon as their base, not Ogrimmar. Ogrimmar are an orc city! The bloodelves doesn’t even get their own district in their own architectural style.
At least they can fly in Org, though.
If you enjoy PVP and farming crates, go Alliance! If you enjoy losing at PVP and never getting a crate unless you belong to a 40-man raid in order to do so, go Horde! 
I have a few Alliance ones but that’s only because of when was workingon Stay Classy. I kept a couple because I like them.
Otherwise I am primarily Horde.
Personally, I play on both factions. Once factions stopped being important in the game, my patriotism to the Alliance faded, and I tried playing as the Horde. I actually enjoy it, and I don’t see the point in limiting myself to just one faction.
“Anduin, we have a Horde spy amongst our ranks.”