How is late game tanking and breakdown of each?

[Nihility]

WAR is extremely simple with one huge annoyance and two great skills that clash so you need to be careful on them.
the annoyance is storm's eye. It takes 3 gcd to get it up and you need to maintain it but aside from the buff it's trash compared to storm's path and with your bigger skills weaved in once in a while the buff from this is almost always going to delay your cooldowns, be forced to refresh way too early, or be forced to let it fall off for 1-2 gcd. It rarely lines up properly outside of the opener where it lines up near perfect.
the clash is infuriate and inner release. Never ever use these skills together or your costing yourself like 20-30k+ damage easily

DRK is like WAR but it has a bunch of skills with annoying downsides and it's version of storm's eye is pretty awesome
dark mind is absolutely useless against physical attacks
living dead is bar none the worst invuln skill. The way tank hp went way up compared to healing output it is more of a healer resource black hole than ever before
abyssal drain and salted earth are straight up remnants that they just left in place and are barely worth using. Just super weak skills you just use because it's better than not using. Even Carve and spit is kind of some weird wedged in thing as it is now(it is actually good though) Much rather see these skills effects just be rolled back into bloodspiller/quietus and the new shadows skills
and the blackest night is the only defensive cooldown that shares offensive resources across all tanks. Personally i think this one is not a problem though as it's cooldown is negligible
so the resource is the more limiting factor in it's case

PLD is easy to use and you get to use a lot of different skills all the time because it's basic skill rotation is super long but also simple to grasp and it's burst is also different skills than it
normally uses. It's only real downside is very long cooldown on it's invuln skill

GNB is very very busy. It's very strong but definitely keeps you going nonstop so be prepared to be pushing buttons very fast, very often

As of right now PLD and GNB are pretty much the very solid tanks that don't need any tweaks and are just a preference of playstyle
WAR and DRK share a playstyle
WAR is a bit undertuned on the damage side which seems unbelievable but outside their bursts they kind of suck
DRK is on par but has a bunch of negative quirks to their skills that need to be ironed out. S-E just needs to get the idea that dark night is some sort of undead anti-mage out of their heads. It was never that and isn't even that in FFXIV's lore and it's weird that they call it the magic tank when in reality it's just the least physical tank since every other tank is omni-damage reduction