I was active duty infantry in the army for a while. Was a team leader for a weapon's squad, and briefly a squad leader before I got out. If you want to experience the best / worst days of your life, join a combat MOS (job). If you want to use the military to significantly boost your success in life once you're out, join a job that you can make a career out of once you're out. Anything in STEM would elevate you way beyond your peers once you're out.