So.... I'm going to have to say a few unpopular things.
I used to play back during WoW during the "Three Sunders" rule. I didn't play a lot, but I did do some tanking, enough to easily get an idea of what it was like. I did tanking during ARR, near the middle until I got tired of people expecting me to know my way around dungeons with optional ways to go and optional mobs, and expecting me to know which I should pull and which I should skip even if it were the first time I was there. I tanked on-and-off through Vanilla, TBC, Wrath, just a smidge in Cata, a bunch in MoP and a little in WoD, and once-or-twice in Legion and BfA.
I tanked in FFXI.
So I feel I've a decent amount of experience of tanking across three different games, and well..........
All of this "Enmity Management" you guys are harping on about? Can you guys please take off the rose-colored goggles for a second? Enmity Management was never really a thing for tanks. You simply spammed the skills that had the highest enmity gain, and usually, especially for early WoW tanking, these skills did jack all for damage. I twas all about "What skills do the most enmity so I can keep the enemy on me"? You want to harp on about low DPS? That's laughable, because tanks did far less DPS back in those days.
"Enmity Management" was always about DPS not overshooting their tanks, and it was a crutch to slow DPS down and to make them wait before actually using their highest DPS skills, and it was also a crutch to limit healing. None of these had any impact on what the tank was doing, because the tank, yet again, was simply spamming the highest-enmity routines they could do along with whatever defensive cooldowns they had.
Also, "Stance Swapping" is something else I'm getting tired of hearing about, when tanks wanted to run with DPS stance because somehow they weren't doing enough freaking DPS that without a button that says "I DO MOAR DPS NOW!" they feel like they are doing less DPS (even though they aren't). Same with healers complaining about the loss of Cleric Stance; that DPS was baked into them without CS but yet healers still think that without a toggle "MOAR DPS" button they feel like they aren't doing DPS.
Back to the OP's actual question.....
PLD is the funnest tank to actually play because you have the most mitigation buttons out of any job:
Sheltron: You are popping this anytime you are anticipating big incoming damage.
Cover: I've saved peoples' lives from this. Someone with 3+ stacks of Vuln about to take a huge AoE hit? Yeah, I've done that. It feels awesome.
Passage of Arms: Boss is about to do a huge AoE and I pop this and we barely survive because people messed up the "boss buildup" mechanic? That's usually worth at least 3-4 comms at the end of the fight.
Clemency: I love popping this on the healer to save us from a wipe and/or the healer goes down with 20-30% left and I manage to keep myself and a DPS alive until we finish off the boss.
Shield Slam: For trash mobs with annoying attacks when your group doesn't have WHM (or low level when WHM doesn't have Holy yet) and/or the few early bosses that aren't immune to stun.
And of course you have your standard Rampart and your 30% less damage button like any other tank does, as well as Interject and Provoke, and Reprisal (which makes enemies do less damage).
I find myself, when I'm running lower level content going "blah... no Clemency?" or "Meh, wish I had Passage of Arms there.."
As to your rotation?
Later levels, you have 2 Rotations, or well.... the first 2 buttons are the same and you end with either DPS or DoT. Late Level, you get Sword Oath, finishing the DPS rotation gives you 3 charges of an even more powerful skill which is great for building a bunch of MP back fast. Your AoE later on is a 2 button rotation, and you have an oGCD AoE as well, as well as an oGCD single-target attack. Sheltron gets thrown in either to soften the tankbusters, or to help deal with a lot of incoming damage (like when you're pulling large groups of trash). You also get a "Dump MP to do crazy AoE Damage" rotation that involves popping an oGCD+4 casted spells+finisher.
Tanking in FFXIV is about knowing when to use your mitigation buttons as far as trash packs go. Spacing out your various buttons, and planning ahead, as well as dodging all of the AoEs (which get more common, esp in Lv80 dungeons). Nothing like pulling 7-10 mobs and each of them are throwing AoEs down on the ground every few seconds and you have to keep dancing and weaving around them while doing your rotation while keeping track of your mitigation buttons so the healer doesn't run out of skills to keep you alive. An awesome tank vs a reasonable tank vs a crappy tank, the difference is night and day when they try to pull 2+ groups. The tank that stacks all of his mitigation together with a macro vs the tank that knows which should be paired with which.
For boss fights, it's far more mechanic-heavy, knowing what bosses do and how to deal with it, knowing what the tankbuster attack is called so when you see it come up, you react to it before you get 70% of your life sheared off in an instant because you didn't have any mitigation up at the time, knowing where to position the boss, some bosses should be tanked at the edge because they have nasty AoEs you don't want getting dumped on the rest of the group.
The 8-man fights, sometimes the two tanks need to be working together, and be in agreement as to who does what (Thornmarch, Leviathan, Susano's sword phase, Titania to name a few). Also need to be paying attention, if the main tank dies, you need to be ready to step up to the plate quick and need to know the fight yourself so you don't get killed too while they get the other tank back up, etc.
WoW places a lot of emphasis in pushing the buttons in an optimal order, FFXIV places that emphasis elsewhere.