Questions for people who had to make a choice like this- Did you guys have like that feeling (if you were tied) and you were like this is it... this is the one for me. Or was it just like let me pick one based off of this one thing and get on with it?
I had to make this same choice two years ago. To be honest, USAFA was always my #1 pick, even before I started the application process. However, I think I would have been extremely happy at USNA as well.
Looking back on the decision, I have absolutely zero regrets about choosing USAFA. However, I doubt that I would have regrets if I had chosen USNA instead. The bottom line is that for someone who is committed to serving our country, either school is an awesome choice. It is very possible that whichever one your friend picks, she will feel that she chose the "right" Academy because she will fall in love with the opportunities and culture of the place. In that regard, it's difficult, if not impossible, to say that there is a "right" and "wrong" school.
However, I would caution against "making a decision and getting on with it". The choice isn't one that should be taken lightly, nor does it need to be made quickly (most people don't even receive appointments until March/April). I would suggest that she talk to current AF/Navy officers about their respective branches and the lifestyles involved. IMHO, the most important factor for her to consider is her career after graduation. Would she rather be on a ship or a land base? Which branch offers more accessible career options for her area of interest? If she wants to study something specific, which school has a better program in that field (this may even be a tie in lots of cases)? If possible, she should also try to talk to current cadets/mids and/or recent grads from both schools.
I really like
@697biling's advice from the USAFA grad. It is spot on, and I think that is a solid way to look at the decision and its consequences. If I were her, I personally wouldn't decide based on whether or not I needed to cut my hair during Basic (as someone else mentioned). Regardless of her reasons, though, she likely won't go wrong if she is truly committed to her choice. Good luck and congratulations to her.