Well it's an ensemble cast, so they all have their parts to play and there isn't really a main character. That said, I enjoy Jeff's personality (similar to mine), and Troy's stupidity tends to be funny more often than not. But mostly I enjoy what the show ends up being as a whole, after all the characters do their thing. Strangely hard to pin-point a specific character that I really enjoy on this show.
But Abed is definitely one of my least favorite things, probably only outdone by that she-beast Shirley.