For melee builds you’ll likely need the attack speed and life steal from Revenant. That’s especially important on Infiltrator, since Inquisitor class have no native attack speed boost.
Also Revenant is in your route to get Dying God/Yugol or Ultos.
For casters or Leviathan route Elemental Storm is pretty good option. Here’s my FoI Infiltrator going heavy in purple/green territory.