I don't watch a whole lot of standup, but I find Robin Williams extremely funny! He talks so darn fast you have to listen really good, but he many times, has one joke after another.
I remember Joan Rivers. She used to be really funny when she first came out. She's gotten sickening and not so funny anymore. I can't stand hearing her talk.
Also, remember Don Rickles? You either hated him or liked him. Took me a while but I got to like his "insulting" humor at times. Also, Alan King?
TIS