You know, I found Angelus incredibly funny... in a twisted, dark, evil kind of way. I'm serious. Dude had a sense of humor. Also, any scene containing Angel(us) and Spike was funny. I especially liked their fight over cavemen and astronauts. That had me howling with laughter. And Wes! My God, uptight Wes was the funniest. I love his prat falls. And that squishy face thing. One of the funniest hours of TV I've ever seen in my life was Spin the Bottle. Most of that was thanks to Wes. To be fair, though, Angel's "tiny minstrels" comment gets me every time. With these guys, the funny was more in the acting than in the lines.
Overall, though, I think I lol most often at Anya. Her dialogue is great. Almost every line is funny. EC delivers it well, too.