I vote for Air Force, as I have a strong attachment for it. My dad is ex-Air Force, and there are a lot of British (and US!) air bases in the general geographical areas. A lot of the lads round here join up just to get the hell out of here!

P.S: Good luck with joining the Marines, loinharte! I actually have a friend, on another board, who joined not long ago. It's tough from what I understand, but worth it.