Question in the title. People often complain about what they don't like, but that isn't as useful feedback, I don't think, as saying what we DO like and WHY we like it, which can inform future designs. Though...I'll probably mention a few things I dislike.
I'll start:
I have PLD, WAR (just recently), and GNB at 90, DRK at 30 (just messed with it a little, so can't speak to it as much)
Of the three, I've decided I like WAR best.
WAR's entire rotation is MORE OR LESS set up by level 50 (Storm's Eye), so you no matter what content you sync to, you generally can do the same basic thing across all levels. While some may dislike this, I like my CORE rotation being the same across levels since I can use my level 90 muscle memory anywhere. I love how the additional complexity it gets as you level comes from upgrading abilities or giving them special interactions (like Infuriate + Fell Cleave) rather than bloating my hotbars with tons of buttons I still have to have a spot for but only press rarely. This keeps the Job feeling fresh as you level, while not making it difficult to navigate on a controller/with fewer hotkeys, but also giving the Job a SMIDGE of nuance with said interactions.
The rotation is simple, but intuitive, leaves ample room to weave oGCDs as needed, and Fell Cleave spam is...oddly gratifying. WAR's reputation as "the other/blue healer" is also well-deserved, and while probably a BIT too powerful, lets WAR feel competent in all content in the game, even if it has the lowest (statistically tied with PLD) damage cap, it also has the least variant between lowest and highest, meaning the Job is easy to learn and get relatively competent with. It's probably the single best choice for people new to tanking to get into the role. The base rotation including self-healing means even before getting Raw Intuition, WAR feels smooth and safe to play, which also makes it feel good in prog and while leveling alike.
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GNB I somewhat like because the rotation is rigid enough it doesn't require a lot of thinking and can be done reliably throughout a fight without really "getting lost", but it is kind of painful to maneuver the boss or use oGCD mitigations during Gnashing and the burst window, and I kind of dislike how the 90 sec Bloodfest CD doesn't line up with anything (I'd rather it be 60 OR 120 sec, honestly). Double Down is an oddly fun button to just hit and watch the animation of, though, and GNB's overall burst phase (Double Down into the DoT into Gnashing, finish the third hit of your base combo, finish with Blasting) feels really tight and good to pull off.
Overall, the rotation is smooth, has a generally nice flow to it, and is fun to roll through, and the burst feels satisfying, but it can feel a bit inflexible at times.
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PLD was my tank of choice in SB, but the loss of the three combos (DoT, Threat, and direct damage) has somewhat changed the Job. Requiescat makes it more flexible by giving it more ranged potential than the other tanks, as does the Sword combo at the end. It also has a TON of utility.
But part of my DISlike of the Job is how much this changes the Job if you sync to do literally anything, even something at level 89. The Swords replacing the first Goring combo of your melee cycle leads to some weird muscle memory issue when doing synced content and having to swap to leading into melee with Goring instead of Royal as you do at 90. The Job also loses the caster phase entirely if you do anything below level 68, which is roughly half the content in the game. It also loses a LOT of its self-sustain, especially below level 58 and Clemency.
The Job is fun if you can really lean into its party buffs/utility, but it feels kind of disjointed leveling/syncing, similar to BLM. Though it is fun being able to go full Ranged physical-lite for 7-8 GCDs and unleash Ultimate Bladeworks on your enemies and use Guard to keep the last healer alive long enough for the to Raise/LB in critical situations. Overall, I feel PLD has a lot of buttons to do basically the same thing even WITH the Caster phase being just pressing the same button over and over. It is definitely the most button bloated of all the tanks I've played, and Atonement just feels...I dunno, kinda there. It doesn't feel good like Gnashing/Continuation does to me, though I can't quite place my finger on WHY.
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So I like WAR best (smooth, simple, intuitive, flexible), GNB somewhat (smooth/tight, satisfying, but less flexible), PLD's okay but probably the least (weird syncing, very flexible, but also a lot of hotbar buttons and CDs to work through that somehow doesn't feel tight like GNB's), and...presently have no position on DRK yet. (I'll level it eventually, but I'm not much of an edgy-boy)
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So, what about you guys?
Which do you like best (can be more than one)? What do you like about them? And sure, what do you dislike about them?