Are you aware that the army gives out the most scholarships? If you are interested in the Army (and there are a lot of options within the army) then I would strongly recommend applying for the army scholarship too.
I am assuming you refer to AFROTC and NROTC COLLEGE scholarships? If that is the case as I think it is, IMHO, apply to all ROTC Units at your preferred college or colleges. As @AROTC-dad says, just make sure you are willing to serve in that particular branch! One of your favored colleges may only offer NROTC, while another may only offer AROTC, hence check your preferred colleges, get accepted and apply for those ROTC scholarships at those schools that you feel fit your service desires.