If classes were cars, the Protection Paladin almost drives itself. At my current level (62), I have two heals and a wide array of armor buffs. Protection Paladins have a reliable solid tank that really doesn’t take a lot of self-management to keep running.
The clanky clanks and chime sound almost make me feel godlike as well 
Prot paladin is strong. They’re a bit squishy between sotr procs but they have unmatched utility. Extra cleanses (including a mass aoe cleanse in pvp) hand of freedom, spot healing with hand of the protector, et cetera. They can cheese certain mechanics, such as necrotic stacks with BoP and Divine shield, and they do decent damage. Their main faults are the squishiness between sotr procs and that they are weak at kiting.
Prot Warriors, which are my personal favorite, are basically the kings of mitigation when you cycle your CDs correctly. We take very little damage from most things when played right, but lack a consistent heal (until you get good at sniping killing blows.) Warriors are very easy to kite with and have loads of stuns. It’s also super fun to hit a mob with its own spell using spell reflect. Best thing though is that the DPS is insane for a tank. Cons are that you are healer reliant outside of a few cds if you aren’t getting kbs. (Love explosives week. <3)
Blood DKs take loads of damage for a tank BUT, and it is a big but, they can easily outheal a healer when played correctly. They do decent damage and have massive utility in the form of death grip and gorefiend’s grasp. They’re a bit weak at kiting due to mediocre movement abilities. They’re also easy to play, possibly the easiest tank spec.
Brewmaster monks are the best raid tank, and take very little damage when played correctly due to stagger. Their damage is okay, and they have some handy utility in ring of peace. They’re amazing at kiting due to torpedo and their teleporting ability. They’re also easy to play, fast paced, and a lot of fun.
As for vengeance and guardian, I do not have either one at max level and have never tanked challenging content on either. Haven’t really heard much about vengeance but I have heard that guardian is in a bad spot atm.
I’ll add anything I missed if I think of it.
Prot warrior is fun. Get to jump around, charge your friends and enemies, do good AoE damage, got some cooldowns and stuff, … hmm… I dunno.
I have a 397 prot pally, 384 brewmaster monk, 359 blood dk, 380 vengeance dh.
Here are my thoughts and opinions on them.
Prot pally: can take a hit, can mitigate damage, decent aoe threat, group utility. Has gaps in the rotation where you’re waiting for 2 seconds for something to press. Otherwise good tank.
Brewmaster: best tank at taking hits due to stagger. Great mobility. Terrible self healing. Stagger allows you to smooth out your damage intake but you need a healer. Rotation has you constantly pressing something. Stagger can be overwhelming until you get a grasp on the mechanic.
Blood dk: amazing self heals and self sustain. Can take a hit but your health will yoyo and scare healers. Good aoe damage/threat so far at 359. I can tank regular mythics and pull 3 groups without dieing. Super slow moving tank but you’re a powerhouse due to self healing and mitigation cooldowns.
Vengeance dh: probably the most fun tanking experience I’ve had. HP is same as DK. Yoyo effect. Good damage as a tank. Decent self sustain but not as good as dk imo. Mobility is awesome. You can freaking glide across an entire zone. You look awesome. Spell affects are cool. The only problem is they lack in consistent mitigation. You have demon spikes and meta and self healing. Thats about it. Outside of that you better kite those mobs like a beast.
These are all my opinions and purely based on pve.
I don’t know anything about PvP so I won’t talk about that.
Brewmaster - Most fun and easiest tank to level thanks to black ox statue. Most powerful raid tank, decent in M+.
Blood DK - King of Dungeon tanking, limited mobility makes it feel slow in open world content (recommend Engineering for Nitro Boosts if you decide on DK)
Druid: Very weak now in progression content but still totally fine for tanking Raids/LowM+ and Battlegrounds and what have you. Simplest tank class to play. Most distinguishing feature is that this is the only tank class that can also spec ranged DPS. Druids also have excellent quality of life in the open world from travel/flight form.
I lost me at sitting in LFR
I’ve never run a tank before BFA, and to be honest I was scared to do it, but I bit the bullet and rolled a Blood DK and so far it’s been pretty darn good.
pallies aint squishy. Proper azerite traits and haste make us pretty beefy right now.
I also don’t PvP, but I roll all tank specs at 120 in M+
Here is what swings it for me though: I want to be able to help the group, not “just tank.” So I like Paladin and Monk due to dispells, off heals, bubbles, and crowd control. Those are my fav two tanks due to that. Even though I like Warrior, I get very frustrated when I can’t help others in the group when I need to.
I’m not so sure about that anymore. Prot warrior has by far the highest physical mitigation and the highest damage output by a mile. I highly suspect their dps will get toned down in 8.2. You can always bring another class for battle res or if you have an engineer in the group they can battle res as well.
As of this very moment a prot warrior makes up nearly 60% of the top 100 M+ runs (+21 or higher keys).
Prot Warrior is currently highly overtuned, that much is obvious. But utility-wise they have nothing that can compete with Death Grip. I think it’s highly unlikely that they’ll keep doing twice as much damage as all other tanks for very long.
I’m a guardian druid, I can’t sell it right now 
Relative to monk/warrior you are when sotr isn’t up. Overall though, prot pallies are sturdy, yeah. They’re my second favorite tank too.
I was trying to give unbiased information on the tanks based off of my experience with them, which is through 10s with all of those I listed (with the possible exception of monk, don’t remember how high I went with monk) 15s with the warrior. Last season more than this one, been busy lately.
Most tanks are in a good spot right now.
even w/o sotr we can still do pretty good with cooldown rotation + bulwark(azerite trait)
in raid my sotr always feels like its up when i need it.
In m+ it honestly doesnt matter because I can just kite if i need to.
In BfA I have experience on two tanks, DK and Paladin.
Paladin has a stupid amount of utility and survive-ability. Lot’s of buttons to press and very engaging. Avenging shield procs like mad and it’s super satisfying to be able to silence ranged mobbs and or completely lock down a mobb by yourself. Good damage and good magical mitigation.
The downside for paladin is limited uptime on active mitigation until you get a good amount of haste. So big chain pulls in M+ can be a bit hairy if you don’t have enough haste to keep 100% uptime on SotR. That said, when SotR is up, pretty smooth damage intake which makes healing them more enjoyable.
Prot paladin brings: An external CD that can be used on a party member (identical to a healer external), BoP, Bubble, Lay, the ability to rez, and freedom. Many of which will allow you to completely negate deadly mechanics.
DK is also very satisfying to play. The toolkit of this class is a dream for M+, and they are highly sought after in M+, for good reason. At 407 ilvl on my DK I can virtually pick and choose what runs I want.
DKs have 100% uptime on active mitigation which is nice. However, they still take a lot more damage than other tanks but also heal for a significant amount more than other tanks through Deathstrike. Deathstrike heals you for an amount based on how much damage you have taken in the last 5 seconds. Most of the time your healthbar will be a ping pong ball, which can be stressful for healers but a non-issue for a good tank.
Mass grip and grip are probably the two most useful utilities in M+. Being able to move mobbs around via grip (which also acts as an interrupt and a taunt) is amazing. Then you can spec into DnD slow, which means you drop your aoe ability and everything gets snared by 90% and drops off 10% every second. This means kiting is a joke.
They have battle rez and AMS which allows you to straight up negate some mechanics.
They have the ability to control undead which is extremely strong in dungeons like Atal and KR where your add will end up doing 10%+ of your overall damage.
DK’s have a ton of CD’s: Bonestorm (1min), Dancing rune weapon (1.5min), Vamp (2.5min), Icebound Fort (3min). So basically you are constantly rotating CD’s, and that feels good.
I don’t have experience with Warriors in BfA, but I did alt one in Legion, that said warriors have recently claimed the throne in M+, pulling just ahead of DK’s in the communities eyes. The issue here is there is a high skill ceiling. But the class is fast paced and does by far the most damage of all the tanks.
I main a VDH.
I do fine in everything I have tried (just up to 14 in M+).
I don’t raid, other than to get the achievement and maybe a specific piece of gear, but we suck in a raid situation beyond Heroic.
I absolutely agree. Again, I’m just speaking relatively. 
I’ve only ever played 2 tanks before, but I will say that the Blood DK was some of the most fun I’ve ever had. The whole life leech thing is amazeballs. The damage wasn’t terrible and I know a couple expansions ago they could solo through some dungeons(minus bosses). I mained it in PvP as well and actually did fairly well.
The other I played is a Protection Paladin. Not very fun at all. You do terrible DPS(unless you’re pulling mass mobs) and without a real healer you’re not that effective at even staying alive under high DPS. Also I dueled for like 30 minutes against a friend just to test out survivability vs my Retribution spec and I really couldn’t tell that much difference. Apart from the extra health. Maybe if I got the rotations down better I could be more effective, but not that much more effective.
Currently with Prot Warrior, we like to squish the other squishies with Thunder Clap. Not good enough? Pop Avatar with the Unstoppable Force talent to squish harder.
Thanks everyone for your responses.
I think at this point it’s a debate between Prot Warrior, Prot Paladin or DH.
It was about 2am and it was an Uldir LFR. Understandable that the tanks were in short supply at that time.