Aesthetics and dps rotations despite being similar in many aspects and sharing literally the same mechanics most of them.

PLD: have a rigid rotation, pretty unique until you hit requiem cast, have 1 cd less and some niche skills like passage of arms and clemency that tend to collet dust on your skill bar.

GNB: the most unique tank in terms of dps have a rigid rotation too, all his skills are useful on every situation probably bcs is the new guy on the town more than anything else, is the only tank without an inner release window thank God.

WAR: a pretty simple and straight forward tank have some unique perks like nascent flash self-healing but is the slowest tank since almost everything is GCD based, still his mechanics works pretty well between each other, just have inner release which is like requiem cast.

DRK: it's just a simplified WAR on every aspect without the unique perks the other have, the only thing that have compared to WAR is a window of throw all your oGCD during 10s and then is just 50s of slow simplified WAR gameplay, his most distinctive aspect is how strong TBN is and that's all and don't fool yourself about the MP management it doesn't have any, the moment you learn how it actually works is theoment you know you don't actually manage anything, delirium is just inner release.

Of all tanks I barely only enjoy GNB bcs is the only one that is not a WAR copy somehow, anyway just level all of them, make some research about how to properly play them which it's not hard considering how easy are all of them right now and stay with the one you like more.