Choosing Bio makes it easier because for the most part, all the med school req. are also req for your degree. So that way you don't have to struggle so much with you schedule to fit everything in. But, like it was said, choose something you enjoy and can stand for 4 years of study.
Personally, I majored in Bio (because I love it), minor in chem(because it is only one more class than I needed anyway), and a minor in philosophy(just to mix it up). Getting a minor is something you enjoy is usually pretty easy to work with.
Do what you enjoy but a degree in a science works pretty well.