As to what undergraduate degree is best...that's debatable. Most pre-med students major in one of the hard sciences. Bio, Chem, and Anatomy are very common. Physics is an option, but much less common.
You really can major in anything as an undergrad. If you want a private practice, majoring in business may help. An argument could be made for some of the social sciences, like psych or social work, since you will be dealing with patients and people at their most vulnerable.
The choice is really up to you. You may want to talk to your guidance counselor, who should have many more ideas.