Eryca,
Coming from someone who did Air Force ROTC for a year, I'll tell you somethings about the Air Force.
First off, the Air Force supports a completely different mission than the Marines do. Its a completely different mentality and your going to either fit in, or your not. That simple. I wasted a solid year of my life with the Air Forces program only to see it wasn't for me.
The Air Force is about air superiority, space, and missiles. If thats what you want to do, fine. Just know your career is going to be very different than the Marines.
The Air Force does push for you to finish that degree, but if you go enlisted, it'll be hard to make the time trudge through it depending on your job.
If you decide to go Marines, I would honestly say, earn your degree first. If you can find a way to pay for school (student loan, scholarship, etc), PLC is the best route IMO to becoming an officer. I've met some guys who went the reserves route to pay for school and it set them back for quite a while.
Find out what you want from your life. If your going to come join the Marines, realize your going to be a Marine FIRST. Everything else comes after that.
If you decided to go Air Force... Well, good luck. I don't have to many good things to say about it from my experience besides they've got nice toys and clean bases.