Daniel Tosh (never watched his Tosh.0 show, I'm a fan of his pre-Tosh.0 days, didn't even know what his show was about, you HAVE to see his actual stand up comedy)
Greg Giraldo (if you like offensive, apply here)
Dave Attell (see him after you watched Greg Giraldo, he crap on all that was still left sacred)
Jim Gaffigan (his take on sloth, laziness, gluttony and complacency is timeless)
Robin Williams (will forever be one of the best)
Jeff Dunham (one of a kind, he's flawless as a coordinator of hand and mouth for his ventriloquism stuff, and has great regular stand up as well)
Lewis Black (actually friends with Larry the Cable Guy, his "angry-man" schtick never gets old and his barrage of ironies and disappointments are classic)
Bill Cosby (delivery and timing cannot be emulated)
Ron White (honestly the funniest of the 4 from Blue Collar)
Mitch Hedberg (a sad loss to the comic world)
Demitri Martin (mundane becomes hysterical and the spotlight on ironies is genius)
Frank Caliendo (best impressionist. ever. period. still has great jokes too)
Jerry Seinfeld (show was great, standup is even better, his stuff is still, literally about nothing, but something's still funny)
Pablo Francisco (his energy is unforgettable, and imitations and sound effects solidify his brilliance)
Gabriel Iglesias (possibly the funniest "clean humor" comic working today, excellent timing, sound effects, voices and timing in his stellar stories)
Brian Regan (reminds me of Will Ferrell's nuttiness but has more intellect added in, great subject matters)
Nick Swardson (never left his teens, but has well-aged sense of humor and perspectives still)
Kevin Hart (there is something about this tiny man's delivery and stories that makes my stomach end up hurting)
Larry the Cable Guy (he comes off like a moron but is actually a scholar and a genius in reality, I don't care how overdone his catchphrase is, his jokes are still hilarious)
DL Hughley (another one with great delivery and great subject matter)
Jimmy Dore (doesn't really stand out for anything except for the fact that he has nothing that stands out and still ends up being hysterical, although his humorous bitterness is memorable)
Tom Papa (his childhood stories and adult failures fuel the hilarity)
Paul Gilmartin (pessimism becomes sidesplitting here)
This is a stream of thought post, so I might be forgetting some fav's but it's a solid start. I got to see Frank Caliendo, Dave Attell, Gabriel Iglesias (met him w/ picture taken) and Rob Schneider (again, met him and got autographed shirt and pic taken)...I have an obsession, almost, with standup comedy and the art of it, only because I find it to be some of the sharpest concentration of humor in the universe, and I have nearly 200 different routines and specials in my possession, both on physical and digital medium. I just won't put any on unless my rectum is behaving that day.