Both offer interesting enlistment opportunities.
If your goal is to complete two years of college as part of your enlistment, I would recommend the Air Force. Air Force technical training often (but not always) contributes to an associate's degree through the Community College of the Air Force (CCAF). See here for more information on the CCAF:
http://www.au.af.mil/au/barnes/ccaf/index.asp
There are some complaints about the CCAF degree...but it is accredited and I think the AF is the only service that has structured their career field technical training to grant community college credits (I could be wrong about that). I formerly was in charge of technical training for a specific career field (officer and enlisted) and first hand observed the CCAF emphasis with which curriculum is developed. This is generally a good thing, but not always. For example, there is a training script, and no matter who the instructor is, the training outcomes are always the same. In a "real" civilian college critical thought is emphasized. Whereas in military training, task knowledge and task competency is emphasized, but your understanding of the "big picture" is quite incomplete. That's a key difference between "training" and "education."
Be aware, however, that Air Force enlisted culture is fanatical about completing the CCAF degree (or at least your senior enlisted leadership)...to the point of not promoting you at a certain point in your career if you do not complete it. The Air Force has a serious cultural problem right now that places job performance too far down the totem pole in importance in relation to a slew of other things that are steeped very high in bull$hit. Google "John Q Public" to get the low-down on many of these issues. This JQP blog is extremely lively, sometimes (often?) informative. I disagree with some of it, but overall it will lay out some of the real warts in the Air Force that *do* exist (but the Air Force itself is reluctant to address, let alone allow a critical discussion to take place or dissent to be voiced).
Even **with** all of these problems, I would still recommend the Air Force over the Navy. There are numerous career fields that provide translatable skills and there is a strong emphasis on education (although perhaps too strong). Just my two cents.