Enig or CoH
I rather like Enigma (15% ed Archon) on my lvl 89 Trapper and have CoH on my HF Merc. The ll particularly is helpful for him and I really like being able to Tele for transportation as well as preserving my Merc's life. I dont think I would enjoy having it the other way around.
As a side note I have several % Res all and with Fade I'm good for resistances. I would probably prefer CoH if I was lacking in the Res dept.