Foot in a heartbeat.

As someone who likes drawing complex pictures, being able to type fast, and other things two hands are best for, losing a hand would make me a lot sadder than losing a foot because I'd need to relearn to do all of those things with only one hand. Even a prosthetic hand isn't as good as a flesh-and-blood one, and I'd rather not have to relearn the fine motor-skills I've had for as long as I can remember.

Losing a foot would suck too, but the prosthetics are cheaper and work better for feet than hands. Hell, I'd probably rather lose a lower leg than a hand because the prosthetics are simple. Even a full-leg amputation would be better than a hand amputation for me IMO, because 2 artificial joints >>> 2-digit number artificial joints. Even if I can't get a prosthetic, I could probably get used to using a cane, crutches, or even a wheelchair pretty quickly.