I say the hands because thats we mostly use to win

glutes

glutes, shoulders. if anyone plays aikido/freestyle....i think they would agree. almost every game my shoulders and glutes saved me.

I'm with toritori on this one. So many times have I been in Judo, almost down for the count, and with a sudden and unexpected
CONTRACT NECK!
dismembered all of my opponent's joints for a quick DQ. Good stuff.

All of them together. I don't think there is a most important joint. Or if there is, I have no clue what it could be.

Im guessing glutes and chest, atleast in TKD

All of them... I think.

since people agree on a couple of things and a few say its all of them i say!!

ITS NONE OF THEM

you can't say glutes or shoulders, because they are two joints, you would have to say left glute or whatever. I think that they are all important, some more than others. I gave chest as my answer because it is the most important of the joints that isnt part of a pair.

Neck.

After all, you loose a heckofalotta points by breaking/fracturing it, and combined with your abs it's the most important balancing joint.