i've spoken upfront to colonels in the air force about this question and the resounding answer is choice of major is about as influential in whether you get a pilot slot as is you choice of grub at the cafetaria - null. if it qualifies for rotc scholarship, it qualifies pilot - tho gpa is typically adjusted for engineering majors when considering slots.
and i'm not sure how the navy takes to it, but the air force really couldn't care less if you know how to fly before you go in rotc. they'll put you in some cessnas first, make sure you're not a constant puke hazard, then maybe give you a few joyrides in the back of an f-15/16. but the point is, the air force doesn't care if you have a ppl or not. i recommend you visit an air force det and ask a col up front. this is what he'll tell you. you'll have a little easier time at flight school cause you'll already know how all the radio chat, but that's it. if you still want aviation, hey, it's what you want and that's fine. but keep in mind you may miss the opportunity to make yourself more well rounded by skipping up on a political sci, history or int'l relations degree... and you'll still fly anyway, assuming you get the slot.
finally, purdue uni has a nrotc det and an aviation program. they even have their own on campus airport. the problem tho is it's stuck in the corn country usa. not so bad tho considering it has over 40,000 students. depends on you.