Bumped, because the thread Danny just made will probably be closed.
It's pretty tricky narrowing a favourite moment down from 140 episodes. But I don't remember laughing at a joke as hard as I did during this exchange, in Reincarnation:
Amy: It seems their movements are a form of language. Rather than speaking Ja—
Transition Announcer: ENGLISH!
Amy: [continued] Like us, they speak by dancing.
Also, I could hardly breathe when The Professor stopped to kill Hitler in TLPJF.

I've forgotten a lot of the jokes in Season 7 (been a while since I've seen it), but I remember a few of them being extremely joke-heavy as well.