The shield mechanics adjustments that we have already in game make PLD a very viable tank. If I'm going to tank in a pickup group I think I'd take PLD for the fact that I have more tools to help survive longer when the WHM is not doing his job. Also the enmity threashold is less of a factor in pugs since the avg player's DPS ceiling is well below the PLD's enmity ceiling. So for a pure safety aspect I'm going to take PLD currently. If the group gets going smooth I'll swap back to WAR so that we can kill faster.

When they adjust collusion and nerf WAR's steel cyclone, a MAJOR portion of WAR's merits are gone from a tanking perspective and I feel PLD will become the tank of choice.