Air Force?

So, it was brought to my attention that, in order to get the level of US Government security clearance that I want, I will need to serve in the US military for at least four years. So, I was thinking...Navy or Air Force? So I went over to the recruiting offices for the different branches (they are in separate offices next to each other in a strip plaza thing) and the Navy and Air Force branches were closed. The only office that was open was the Marine Corps. So I went into the Marine Corps office and I asked the recruiter, "What time do the Navy and Airforce open?" The recruiter said, "WE ARE MARINES. WE DO NOT DEAL WITH OTHER BRANCHES UNLESS ABSOLUTELY NECESSARY. IF YOU WANT TO BE A MARINE, YOU CAN BE A MARINE. WE CAN MAKE THAT HAPPEN. DO YOU WANT TO BECOME A MARINE TODAY?" And I was like, "Oh, no thanks". But I gave him my number and such anyways. If they really want me, they can have me. I just need something for four years. I would prefer it to be Air Force.