Also: for the most part (here's where I'll really get the flames), Will Ferrell is not funny. Except when he's doing his impersonation of James Lipton. Even then, it really only works when he's across from Lipton.
Neither is David Spade (except in Emperor's New Groove, and he was well supported there) or Adam Sandler.
Chris Farley was never, ever funny--just painful.
Just in case you think I merely hate SNL, I think most of the early comedians were fantastic, even if they've started to fade now. Dan Akroyd comes to mind, as does Tom--err--John Candy, and of course Steve Martin.
Will Ferrell has done enough for me over the years. David Spade has done some decent stuff as well, and I think Just Shoot Me was an underrated show. Adam Sandler has done his share of crap, but Happy Gilmore still cracks me up, and he's always funny in interviews.
You're right about the early SNL comedians fading, but when watching their earlier work, I forget now why I thought they were funny before. Dan Akroyd, Chevy Chase, and Steve Martin make me sadder than John Candy does, and they're still alive. Let's not even get into Eddie Murphy.
I have to admit I've laughed at some Dane Cook material, but overall he does piss me off.
Oh, and I guess I haven't said anything about George Carlin. I have to admit I'm not too familiar with his standup, but the stuff I've caught him in I enjoyed. I'm definitely sad to hear of his passing.
Anyway, as far as stand-up, I'd probably put Mitch Hedberg and Louis CK at the top of my list, and as far as comedic actors, I don't know that anyone approaches Stephen Chow. Ha ha.