Its a tough call, they are rather different.
British humour tends to be more word play and subtlety these days, whereas American humour is very much in-your-face. I mean lets be honest, American Pie movies are about as subtle as a kick in the testicles

That said, some of the best comedy movies are American, there are several I can watch anytime The Blues Brothers, Young Frankenstein, Cool Runnings to name but a few (In fact I've watch Blues Brothers well over a 100 times and I still laugh, and Young Frankenstein is an old favourite, and the first film I saw at a drive-in-movie in California

). And of course John Hughes is a great director of family funnies. I was watching Uncle Buck and Ferris Buellers Day Off the other week.
I think English TV humour is better, I've yet to laugh at an episode of Friends. But Mr. Bean has me crying in no time at all.
I hope America gets the BBC series My Hero soon, that is incredibly funny

But at the end of the day, I'm a Python man......
Ozzy

Ps. I really liked Johnny English though, some British movies are good
