And this is especially for the martial artists in the forum...
What do you think is the most devastating move there is? I'm not talking ground moves like BJJ chokes and locks. I mean as far as striking, where you can lay someone out with one movement. I guess another way of asking is what is the last move you would want someone to do against you in a fight? For the sake of argument, let's leave out kicks to the nuts.
If I had to guess, I would say a good, clean knee shot to the face is about as brutal as it gets. That's the last thing I think I'd want to experience in a fight. A hook punch to the temple would hurt like b*tch, or a punch to the throat too, or a head stomp, but something about the thought of taking the full brunt of a knee square to the face makes me flinch. And you know you're gonna be spitting out some teeth.