It depends on what kind of Tank you wanna be. I find that PLD offers more supportive abilities for the party.
1. They can spam Stun and Silence (while WARs stun is on cool down)
2. Hallowed Ground is great
3. Cover is very useful to help protect a party members
3. Access to Stoneskin and Protect. Ideally you wont have to use either if your healers are good, but is sure is nice to help stoneskin either yourself or a party member. You won't be needing the MP anyways.
The only issue I have it that it's abit harder to keep aggro leveling up and even in endgame dungeons
