Well, that's a hard question. If you removed all legal consequences, I would choose the 16 yr old girl.

But taking prison time into account, I would definitely fuck a man.

Note: I'm not inclined to do either. One is a horrible moral offense, and the other is just gross.

Actually, now that I wrote those last sentences, I might reconsider. I hate to think that my gag reflex is more important than my morality. That is disconcerting.