When is the best time to exercise, before or after a meal?

Which one is more exercise efficient?

I've tried both, but with pre-meal exercise, the food doesn't go down well when I try to eat right after working out.

I tried to exercise right after eating, but my stomach started rumbling and I felt like something was going to come up.

Since both are uncomfortable for the body anyway, if I have to choose one, which one would be more efficient for exercise?