What am I supposed to do?

My Dad was in the Air Force for 20+ years. My Uncle was in the Army for some years. My older brother is currently in the Air Force. I want to go in the Marines but my Dad gets mad at me if I tell him that. My dad wants me to go in the Air Force. And my Uncle wants me to go in the Army. What should I do? Can anyone give me a description of each branch? What I want out of the military is to be really challenged physically and mentally and to have a great job. What Branch fits me best? Army, Navy, Air Force, Marines?