<p>You need to have a BSN to become a CRNA, but you can also apply to medical school with a BSN as long as you have done the pre-requisites for medical school.
Since you are undecided, you could start in a BSN program. If you wish, you could take the additional classes you might need for pre-med or take them after you graduate if you change your mind.
Once you are in college, spend time volunteering with both, see what they do, see what you like. You can also ask them directly what the pros and cons of their careers are.
You might even change your mind along the way and discover you like something else.
Undecided is OK for now, just work hard, keep your grades high.</p>