Beef between WAR and PLD tanks

[Kyana]

Yes both tank classes can tank.
But if you have a WAR and a PLD in a party, most groups will prefer the PLD to be the MT and take the harder hits.
This doesn't mean WAR isn't cappable of doing the same, but WAR has more to offer than PLD.

WAR deals more damage and it can keep 2 debuffs on the mob, which reduce incomming damage and increase the dmg dealt by WAR and PLD, without generating more hate than a normal DD.
The only thing PLD can do when being OT is dealing a bit more dmg than usual, cast Stoneskin on the other tank and use its enmity combo to apply RoH debuff (usually you don't want to spam enmity combos as OT).

Titan EX is a good example for this, because while both tanks are cappable of filling both roles, the WAR has an easier time gathering and keeping aggro from adds.
WAR+PLD in a party seems like the perfect combination.

If you are a WAR and have a PLD as tank partner, don't go on an ego-trip and try to be MT if the PLD is better suited to do the job.
This only applies to situations where gear and skill of both tanks are about the same level of course.

And yes. I play both tanks.