I was a big fan of Norm Macdonald. His appearances on Conan are classic. But I'd have to say the Jerry Seinfeld is the greatest comedian ever. He's still going strong after over 40 years in the business, plus he had one of the greatest TV sitcoms in history.
Absolutely, Jerry Seinfeld is a great comedian with no sign of slowing down. I love watching the compilations on youtube of Norm Macdonald on the late shows, he was always on top of his game too.
Mort Sahl I love stand-up more than everything (not counting music and movies), so I'll list a few others in order. 1. Mort Sahl 2. Bill Hicks 3. George Carlin 4. Dick Gregory 5. Bill Burr 6. Doug Stanhope 7. Louis CK 8. Mitch Hedberg 9. Dave Chappelle 10. Dov Davidoff