I can't think of a single role I like John Ritter in, even on shows I liked. Something about his acting always rubbed me the wrong way.
The fictional Matt LeBlanc may be my favorite character on a show right now:
A hilarious take on celebrity, UK/US cultural differences, and network tv culture, and in the middle is LeBlanc's self-destructive, impulsive, character who, when the chips are down, is a decent guy.