This is very true, for example conviction is good with Vengeance becouse you are doing elemental damage and it lowers elemental res, whereas fanaticism is good with zeal because it boosts attack speed and increases physical damage and these are the focus of a 'zeeler'.They're all mutually exclusive and the three can't be directly compared.
None of them is more powerful on its own. It's as with rock scissors paper. The selection of the main aura depends on what exactly you want to do with your character and which attack skill he is going to use.Yea, but I mean how good are they? I know conviction is extremely popular. How about fanaticism? Is it less powerful?