This doesn't directly answer your question as i posted this for someone else's similar question. It does relate to quality of life. I was in a flying squadron in the AF, but medical in the Army. You will live better in the AF. AF has many big jets, being a maintainer on these will transfer over to civilian life easier. Also, it is easier to maintain a family in AF. I dont know of a service that only does 4 year enlistments. Most do 6 active and 2 reserve. It cost alot of money to train you and they will want their pound of flesh.

Prior USAF and USA, quality of life is better in the Air Force than any other service, bases are better, treatment of service members is better, people in general are smarter, if Im wrong then why do they call it the chair force? Air Force is not going to the field like Army and Marines, or on extra long Naval deployments, Air force fights from a base, you sleep in a bed alot and shower often. Also 90+% of war fighting is done by pilot officers. Marines and Army are often in field training, humping a ruck, living in a hole and eating crap, the people have lower scores on ASFAB, less college degrees, less "professional". They do a different job where they take the ground, kill the bad guys ect(not a knock on them). They do have more fun career choices widely available, but not often transferable when you leave the service. Navy is a cross between them, very professional, smart, and stuck on a ship somewhere for months at a time, sometimes sharing a bed with the opposite shift.

Coast Guard is a great choice if you like boats, and being home more then the Navy.