More than likely you will want CoH for ubers.I've got the same question actually. Here's my gear list atm
Guillames w/ um, Redeemer, Duress RW, Sanctuary RW, Dracs, Tgods, gores, Highlords, Soj, ravens, plus a slew of resist charms.
I have a decent exile made already in a 40 resist shield, but I"m not using it cause it drops me below max resists. I've almost got the runes for a grief as well, so the only question I have now is coH or fort for the gear I have atm.
PVM ... Grief and dracs, goblins / gores and gulli, treachery ... you dont need LW now and thus can make away with it. Very overrated and extremely inferior to grief with its insane damage boost. COH or forti is not a huge difference, since fort with grief is no biggie as your damage bulk is coming from grief, but if you're a damage freak go ahead. I'd wager if you can stack up those 300 stacked res w/o either COH or Fort, Eni is simply a superior option. Provides % life, dr, 2 skills, frw, more life from all the str saved and the mobility option for organholder runs. If you really need that res ... COH.If its for ubers then use coh and lw pb. If pvp then use enigma and grief war spike.