WAR > DRK > PLD > GNB

WAR is probably the best designed tank in EW. It's got enough ogcds to keep you kind of busy but not too much where timing defensive cds will lead to gcd clips. It feels very smooth after the 6.1 change to IR.
DRK is too font loaded and leaves little to do in between 2 min bursts. It's one combo is monotonous and the only reason why its the highest dps tank is because all it's high dmg abilities are tied to 2 mins and are all ogcds, i.e. Shadowbringer, edge/flood, etc
PLD is too rigid. They removed PLD's third combo but replaced it with Atonement so it really never lost a third rotation and just condensed it into a one button spam (x3). Also has the highed button bloat of any tank job.
GNB is just jank imo. The gcds contradict each other and ogcds are a bit excessive, even compared to DRK.