Whichever fits you best, I suppose.
If your extracurriculars lean one way or the other strongly, it might be sensibly assumed that you could be seen as a better fit there. Overall, public health’s school may be a more competitive school merely insofar as Johns Hopkins is among the world’s greatest medical institutions, and there likely shall be more public health majors applying, but I believe Johns Hopkins takes pride in admitting students to the University as a whole and not shifting standards by college.