For me, it would probably be Jeremy Sisto. I get that a lot. Or possibly Steven Weber. I've had a few people say I look like him too. Both of these guys are kind of douchey, so I wouldn't expect it to be a very good movie.
If you went solely on personality, you'd have to find a combination of Woody Allen, Crispin Glover, Charlie Brown and Ernie from Sesame St.