Let's face it.

- PLD is the worst OT, and even the worst MT.

- WAR is OP. You can't go wrong with WAR, even if you have 2 WAR in your raid. But, you can't afford to be "bad" if you wanna MT.

- DRK is decent, arguably the best MT, and can outdps WAR as OT, but is heavily reliant on the party composition, since it lack the damage debuff from WAR, slashing debuff from WAR/NIN, and extra help from NIN/AST to solve his TP issues (and if you have a NIN, you still need a STR-melee DPS to get the STR bonus).

That being said, the "worst" isn't bad. You can clear every endgame content in this game with 2 PLD in your raid. In fact, I cleared everything with almost always 2 PLD, and I'm gonna clear the upcoming content with almost the worst team composition: 1 DRK 1 PLD, a MNK, no NIN/DRG. At least I got an AST.

This game isn't class-carried. You simply need 2 TANK 2 HEAL 4 DPS and you're good to go. Well, almost. BRD was a requirement for most endgame encouters in ARR, dunno if it will still be true in Heavensward.