Which tank?

[Vyrerus]

One thing to consider is if you like Direct Crits. Tanks do not have Direct Hit innately, so they must meld it, except for WAR, which has Berserk/Inner Release to force them every 90 seconds. This also means though, that in synced content no tank can Direct Crit without food or without gear that is specifically the level of the synced content (again, except WAR).

As far as tank complexity goes, they are all simple. GNB has a new combo/oGCD combo gimmick, but it's easy to get the hang of, and GNB has 99% of its rotation by 70, meaning you get 10 levels where you've pretty much got it all. It is truly very simple.

PLD has the most complexity, but this also means it's harder to excel at it. IMO, it is very fun at high levels.

DRK and WAR are almost interchangeable, DRK has a bit more nuance than WAR, but as has been since the dawn of DRK, this is not a good thing.

If you're just looking to try out tanking for the first time, and you want to get into dungeons where you'll actually be doing the tank job, I'd start with DRK or GNB. They have the highest starting levels for tanks, and have a fairly consistent fun level throughout the leveling process. This means you can jump in and start tanking, learning the ins and outs of the role (mainly how simple it is nowadays) right away, and it'll probably start out more fun than the others.