I personally vote for CoH/CoV. To me it just seems at a much faster pace, without too much worry about equipment or anything. It's rather quick to gain levels, and in large groups the combat can be insanely fun (the large the group you're in the more enemies there are in missions). That and it's something different from the other MMOs which are mostly fantasy. Also, I think it looks better than WoW, and it definitely suffers from less lag. No waiting to get into a server is a bonus as well.

Don't get me wrong, WoW has its up sides, but I'd rather get straight to the fight than worry about equipment. That, and I hate looking just like everyone else.