If I understand it right, applying to med school requires pretty much any old bachelor's degree. So if both your CS and CIS degrees are suitable bachelor's degrees then it really doesn't matter which one you take. (Check the details of the degrees, of course.)
As for the "job market"... you're thinking of Plan B, which would come into play if you didn't get into med school, correct? It's hard to say which degree would be more useful, since we don't know much about them. If you were seriously looking for a computing career then I'd suggest looking for degrees with co-op programs (i.e. they mix course-work with sending you out to do actual work with actual companies), but it doesn't seem like that's your goal.