Short answer: Sheldon.
Long Answer: I’m not a big fan of most major network sitcoms. I can be brought around to certain series when I get inundated with them via syndication, such as Scrubs. And it is certainly true that smaller networks like FX put out a number of good shows, such as Louie and The League. However, I generally stay away from what NBC, ABC, CBS, and FOX have to offer the world. Things like How I Met Your Mother (despite Neil Patrick Harris) and Two Broke Girls and American Idol are pure garbage. It’s just crap that people seem to like for no reason other than that it’s on and they don’t have Netflix or the guts to use that loaded gun under their bed. The Big Bang Theory, on the other hand, actually has something to it: Sheldon.
I like most of the characters on the show (Kaley Cuoco is a refreshingly good female actress on a sitcom), but Jim Parsons’ role as Sheldon Cooper stands out. He actually speaks intelligently and the writers clearly research the science-related jokes they have him say. And unlike the way Simon Helberg delivers the lines for the character Howard, Parsons doesn’t go for annoying nerd stereotypes.
I don’t usually write about entertainment stuff, so I don’t have any genuine way to end this. Here is a clip: