A cure for cancer, for all those who will die after me or have died before me. Also a cure for birth defects, so that we don't have to be ashamed of how we were born. And... Ah, what am I saying. You're not God.
Well you're only mortal and I'd feel bad to burden you with the thing that would lead to the fulfillment of my deepest desire/wish so I'd just say could you please get me an Spicy Italian sandwich from subway.