I have a weird sense of humor and I don't laugh a lot except in my head (where I laugh way too much). Anya is my funniest character though, and Willow. I've said it before and I'll say it again - There's nothing like Anya/Willow scenes. Like in Triangle, hehehe. (And, of course, "It did get a little sexy, didn't it?")
But well, both Wesley and Cordelia are just amazing, on AtS of course, they make me laugh all the time.. (Angel can be great as well, I've started loving his sense of humor.. hehe..)