I didn't feel qualified to answer this when it was posted, so I watched about 65 stand-up specials and am 8 seasons into Comedy Central Presents.

These are my favourites in no order:

Bill Hicks

George Carlin

Russell Peters

Bill Burr

Greg Giraldo

Ricky Gervais

Carl Barron

Richard Jeni

Daniel Tosh

Mitch Hedberg

Louis C.K.

Patton Oswalt

Steven Wright

Tom Cotter's was probably my favourite Comedy Central performance so far. Regan was OK, but Gaffigan's "lady in the audience" voice really pissed me off after a while. Still a lot to check out.