Sid Feder - Best trash talker in the business, he doesn't even have to say anything pertaining to your character and he can still make it hurt.
Azrael Erebus - A really good heel similar to Chris Jericho back when he had a feud with Shawn Michaels that every other wrestling company and their mother tried to capitalize on.
Frodo Smackins - I came into reading some of his threads not expecting much, but was incredibly surprised to find that character had a lot of depth and he fact that his finisher is a Street Fighter reference probably makes him my favorite character on the board.

As for favorite feud, I haven't read enough to have a very reliable opinion, so I'll see if I can read around some more and then get one.