I was commissioned through Navy ROTC (NROTC) at a state university, not Air Force ROTC, but I can echo a few things:
- If you enlist in the NG (army or AF) in many states and you are attending a public university, you can often times get free tuition. My state (Maine) offers tuition waivers for enlisted guard. Also, I'm not sure if the guard offers this, but the reserves offer Tuition Assistance (TA) that can also pay for school.
- Biggest question is, do you want to fly part time or make the military a full time career? A lot of guard squadrons prefer to pick up their own enlisted guys who are a "known quantity" for UPT/flight school, so enlisting and then applying for pilot jobs in local guard squadrons after you finish college is a great way to get into a guard unit and do this part time. Conversely, if you want to go full time, ROTC is a better deal than OTS/OCS (post-graduation) in my opinion because ROTC pays for college. With that said, ROTC doesn't guarantee you a spot in flight school, so you could always get screwed and be stuck on active duty for 6 years as a desk jockey.
- If all you want to do is fly, and you don't care what, consider the Army/Army NG. You can fly helos without a college degree as a 20 year old warrant officer and do it part time or full time. I know two different active duty Coast Guard officers. Both are prior warrant officers who went straight to WOCS/flight school after high school. Both did their time in the Army NG and also got bachelors degrees, then applied and transferred to the USCG as commissioned officers full time. One does SAR/MLE as a helo (Dolphin) pilot and the other is a C130 AC at Barbers Point. My only point is, you can fly AND go to school at the same time in the Army and if you want to fly fixed wing later on you can transfer to one of the other services. Army pilots do it all the time.