I'm currently in AFROTC and I have a buddy who used to be in AROTC so maybe I can give you a little perspective. My buddy said that if he had to do it over again, he'd join Air Force. I personally love AFROTC and wouldn't want to switch, but for some people it's just not a good fit.
There are a few main differences, as far as I gather. The first is PT. My buddy said that in his battalion they pretty much woke up every morning (usually 1-2 hours before Air Force) to form up in the freezing cold and get their butts kicked. He would throw up at almost every PT session. If that's your idea of a good time, kudos to you. Air Force PT, depending on the detachment of course, is much less intense. In our detachment we have sports days almost every week and we only have to attend two PT sessions per week. Plus we offer afternoon PT.
The next difference is Leadership Lab. Army's Llabs seem like they are more relevant to what you will actually be doing in your career (land nav, room clearing, 9 line procedures etc.). Our Llabs are pretty much exclusively to prepare you for Field Training. Expect marching, and lots of it. The one Llab we did jointly with the Army last year was probably the most fun I've ever had at a Llab, if that puts things in perspective.
One important thing to note is that only the top 10% (if I remember correctly) of commissioning Army cadets get the opportunity to go Active Duty. If you commission into the Air Force there is a 99% chance that you will go AD. They are opening up some reserve spots in the near future but they will be extremely competitive. So if your goal is AD, I would go Air Force for sure.
Keep in mind that these are just my observations based on what I see at my University and what my friend has told me about at his University. You'll find that every detachment operates a little bit differently, so your experience could vary greatly from mine. The last thing I'll throw in is that I am a crosstown cadet at my detachment and that is a pretty big factor. It can affect your camaraderie and your motivation, especially if you're the only crosstown cadet, like me. The upside is that you gain a ton of respect from other cadets and even Cadre if you consistently show up and are active within the det.
Let me know if you have any questions about AFROTC specifically, I'll do my best to answer them!