I wanted to go into Navy for Cryptology, it is mandatory out of the country deployment which is cool, and the FBI and CSI will hire you if you retire from the Navy as fast as they possibly can. Air Force has a cryptology program too but nothing near as good as the navy program. There really isn't a best branch, navy and air force are considered the best because you are least likely to die, but whatever job you want is what branch you want to go into. All branches have dangerous and safe jobs.