I'm a Bill Cosby girl. I have a copy of "Bill Cosby ~ Himself" that I watch over and over. It's a standup routine that had to be done in the early 80's, but it's still relevant today. Even though I know the routine by heart, I laugh every time I see it.
To me, a good comedian makes me laugh by pointing out the humor in every day life...someone who talks about life in a humorous way I hadn't thought of before. Ellen DeGeneres, Jerry Seinfeld, and George Carlin are all great at "real life" comedy.