A big question that you haven't answered is how you want to ride. I don't know how much riding experience you have, so this is probably a hard question to answer.
The short answer is there is no short answer. If you are going to be doing tricks and such, you might want a smaller frame. If you are going to be doing non-technical singletrack and trails, you might want a larger frame.
I've seen very good riders with very different preferences, so there's no reason why you can be limited to one frame size. Just make sure you're comfortable on the bike.