I just had a look at a few clips of Bill Hicks on Youtube to see what all the fuss is about. Not surprisingly, I don't find him funny myself, as it's just not my type of humour. He seems like an ordinary bloke talking about Big Controversial Issues, while trying to be all cool and laid back, and use the F-word as many times in a sentence as possible. (Not that I have anything against swearing.)
Obviously I don't know much about him, just from watching a few clips, but his style of humour seems about as far away from Russell Brand's, as it's possible to get. I prefer comedians who do not seem like normal people, those who have a real stage presence, such as Noel Fielding, Eddie Izzard, and Russell Kane. And I find people who are cool and laid back on stage a bit boring, unless they have some really clever material.
Comedy is very subjective. We can't all be expected to like the same thing. I do think that RB is very much a "love him or hate him" kind of person, someone who really polarises opinions. Also his humour probably doesn't translate well to many Americans, it is very British in style. There's actually such a chasm between British and American humour.