Carlin, of course. Bill Hicks, Louis C.K., Eddie Izzard, Greg Giraldo, Daniel Tosh (really good stand up, aside from the show) Lewis Black, Mitch Hedberg, Steven Wright, Kevin Hart, Richard Pryor, more or less in that order I think. There are lots of good comedians, and tons of bad ones, and a very few great ones. I really hate a bad comedian, and a mediocre comedian is worse than a bad one even. But you have to wade through a lot of rock to get to a diamond.