Ace Ventura. And it’s not even close.
This is what happens to most comedians. They’re hilarious in their first few years or so. Think Eddie Murphy with 48 Hours, Trading Places, and Beverly Hills Cop. Then they start to take their self too serious and try too hard. What was once strong humor becomes a forced Dane Cook-like act.
Man on the Moon and Eternal Sunshine of the Spotless Mind are both pretty good. Jim and Andy: The Great Beyond which is a documentary about the making of the Man on the Moon is well worth watching too.