M*A*S*H* - when it comes to American television it is a pinnacle that can't be overlooked.

thumbsup Beats hell out of Friends, Cheers, Seinfeld, none of which have ever made me smirk, let alone laugh.
Another US pinnacle: Soap
Agree on UK comedy. Fawlty, Python, Not the Nine O'Clock News, Ripping Yarns (Palin and Jones), The Young Ones, The Comic Strip Presents, Blackadder, Bottom, The Day Today, Vic and Bob, Brass Eye, Alan Partridge, Boosh, League of Gentlemen, Psychoville etc. all of which have me screeching with laughter.
US is funnier in cartoons than live-action - Duckman, Simpsons, King of the Hill etc.