I did AFROTC and thought that the majority of cadets were brown-nosed tool-bags bent on being throwing everyone under the bus to further their ROTC career - that was my inexperienced, uneducated 19 year old opinion on the ways of the world.

Had I known better, I would have stuck with it. The fight to get a pilot slot gets harder as time goes on. I was barely able to get something by the skin of my teeth and because of the good graces of more than a few people.

Now, as far as guaranteed goes - I think the Navy's BDCP option allows you to get picked up for SNA (Student Naval Aviator) while you go to college with less of the formalities as ROTC, however you will still need to do OCS upon completion of your degree - and you're locked in... fail out and go in the Navy as a non-rate enlisted person.

Good luck however you go - consider the Air National Guard during college (most states will pay 100% in state).. if you're enlisted you may or may not have a better shot a flying for them. It's a 'guaranteed' airframe - but no guarantee of full time work after pilot training, etc.