Go Air Force if he wants to go technical. And this comes from an Army guy. Better living conditions, better looking women, better food, somewhat more relaxed environment. There's a reson the Army guys say "about as close as you can get to being in the military without actually being in the military" about the air force. And this comes from actual experience, as I worked in a couple different multi-service and multi-national units. Air Force lives better, period.
Army was not bad though.
As for MOS, I really enjoyed 95B and 95D. Military Police and Criminal Investigator. Can't go straight in as a criminal investigator but can get there with some college and a few years of service under your belt.
