Well, I've only ever broken one bone before and it was my wrist. It wasn't problematic at all, I could move my arm around, make a fist, swim, whatever, I just couldn't move my wrist up and down. A broken leg would be much more hampering.
I think a moderator deleted my post a while ago. Anyway, probably a leg. That way I would still be able to type stuff quickly. Also, if one of my hand was itchy, then I could scratch it with my other hand.
My school's got an elevator, but getting around on crutches sucks, from what I've seen. I like to be able to sit down without being hindered by crutches or a cast. I haven't broken anything, but I have fractured my ankle real bad to where I wasn't able to walk normally for about 2 months, so I had to use crutches, then move to a boot-type thing when school got in, and that wasn't very fun. But if I were to pick an arm, I'd go with my left arm...sorry lefty, but I can't write with you.
Definitely arm, crutches suck, preferably my left, while I would enjoy the opportunity to miss school, it's advocates have forgotten about make-up work, I'd rather just do the work on time.
I walk everywhere and would be lost without a foot. So i most definitely choose my arm, hell even both would be fine, just so long as I can still walk lol.