I definitely cannot just pick one for each category, season six is like a smorgasbord of episode goodness!!
Funny Ones- Tabula Rasa, OMWF, Gone
Scary Ones- Seeing Red, Villians, Two To Go, Smashed
Favorites- Tabula Rasa, OMWF, Smashed, Gone, After Life, As You Were, Older and Far Away, Grave
Fav Quotes-
SPIKE: Hundred forty-seven days yesterday. Uh ... hundred forty-eight today. 'Cept today doesn't count, does it? How long was it for you ... where you were?
SPIKE: (crying) Listen. I've figured it out. Maybe you haven't, but I have. Willow knew there was a chance that she'd come back wrong. So wrong that you'd have ... that she would have to get rid of what came back. And I wouldn't let her. If any part of that was Buffy, I wouldn't let her. And that's why she shut me out.
SPIKE: Oh, listen to Mary Poppins. He's got his crust all stiff and upper with that nancy-boy accent. You Englishmen are always so... (pauses) Bloody hell! Sodding, blimey, shagging, knickers, bollocks, oh God! I'm English!
There's too many more quotes that I love so I'll just stop there before I go quoting the entire season!