Alexander.Lacas said:
Depends fully on the situation, i've tanked plenty of bosses and for example on the pre-sky RotZ bosses they tend to have low acc so Eva was better but looking at a boss like Galarhigg who seem to cap acc no matter how you gear -pdt is better. So generally speaking low acc enemies = eva, high acc enemies = -pdt.
But the whole point here is to choose one or the other. Obvoiusly having both is preferred, but if you only have room for one, which do you choose?
I've done a lot of low man NM's in Abyssea now. From the prespective of the WHM, that PDT is going to save you. The mage can only spam cure you if you live through the TP moves. You are not going to evade much, and would be better off in general planning on countering instead of evading. But in the end, PDT is the better choice if you can only choose one.