I was debating this with my friend today and we came up with the main 2.
-Chuck, because it's actually brilliant the way people go to Chuck when they don't want to be judged (Eric, even serena calls him) because he just accepts the whole of the situation at once.
-Eric, purely because of this from All About My Brother (which struck me as really poignant) "I have a better chance of being happy if I'm honest." which kind've...no one else on the show appears to have figured out.

Anyway, this took up about an hour or two of our time (we're both v. enthusiastic fans!) so I wondered what everyone on here thought. :)