Family Guy and Simpsons are my tops. I know, I have no class... sue me!
The last ones I've watched that actually made me laugh out loud though were:
Big Bang Theory... which hits realllllllly close to home on some subjects and Malcolm in the Middle.
I watched just about all of them in the 80's but now, they're just kind of sappy 80's sitcoms. I can't really watch them and laugh that much anymore.