don't think I could pick just one but Christopher Titus, George Carlin and Larry the cable guy to name a few
Sean Lock http://www.youtube.com/watch?v=SklxlxQ324c enjoy!
My favorite's George Carlin. I can know every line of one of his bits, but he still cracks me up. Great delivery, great choices of subject matter. I'll miss his insight these years to come.