I interviewed at Umass and they have a Medical ASL elective. maybe they have similar classes at other schools? you could have a chance to learn that later if you pass it up now. On the other hand, I think the general consensus is that admissions departments don't care if you have a minor or not. do which one you find more appealing. I vote ASL, it's interesting and would only make you stand out from the cookie cutter applicants if anything
Are you serious? Do NOT major in something simply to impress medical schools. Do it ONLY if you are interested. Even a teensy weensy bit interested. Otherwise, you are going to be absolutely MISERABLE. I know people who are music majors, who have been accepted to medical school. It hardly matters what you major in.
A good grasp of stats will be useful for your entire professional life. And kudos to you if you find it interesting. But if you can achieve a level of competency in ASL, you'd stand out as a candidate.