The problem with stand-up comedy is that it doesn't translate well from USA-to-UK. I think the main reason for this is because of all of the restrictions there are in USA regarding what people would find acceptable/unacceptable. If a stand-up comedian in USA referred to anyone as the N-word, they'd probably never get on TV ever again. In the UK, however, several comedians are known for their racist jokes, and I believe Frankie Boyle dropped the N-bomb twice on his Channel 4 show, and the next week, he was on TV! Personally, I prefer everything unrestricted. I think offence is something that is interpreted, and it is really up to us - the audience - to understand that these are jokes from a comedian, and not a political speech from the Prime Minister! I also feel that the humour aspect of comedy doesn't translate well, either. I would estimate that every other episode of '8 Out Of 10 Cats' has a North American comedian on it, and I always feel they are the weakest or least funny on the show.
That being said, I really love Larry David. He's not so much a stand-up anymore, but his writing on Curb Your Enthusiasm and his speeches at charities, talk shows, and award ceremonies are hilarious. I also love David Mitchell, Frankie Boyle, and Jimmy Carr. Would fuck Katherine Ryan.