Tanks Advantage and Deficiencies

[GeekMatt]

You're asking at a tough time because DRK is new, and SE is currently touching up a little bit if balancing.

PLD has consistently been the safe bet because the mitigation is top notch, but it's lower DPS/aggro. WAR had it's ups and downs but is currently feeling a lot of love in the community (with the exception of a lot of hate for WARs who don't know the time and place for it's DPS stance from healers) because WARs have excellent DPS over the long-term, have excellent aggro and recently improved survival (which has always been heavily reliant on player ability).

DRK is new and you'll find varied opinions of it. It seems to be designed for additional MDF? But for strict mitigation I don't think it has one-up on PLD there. I've dabbled in it and it's a fun job. Healing DRK through DF has proven significantly more difficult than the other two tanks but could be due to player ability. I don't consider there to be anything special about DRK atm, other than it's fun and attractive. I expect future balancing for the job.

If you want to level something while you decide, level Gladiator because it has vital skills that all tanks need.