If you are going to join, have a plan. You know you are going to do six years so do research on things like technical skill advancement (hotel-8 for mechanics, recruiting, drill, career counselor, etc), the availability of bases for you to be stationed at based on your MOS/Rate, how fast you can advance while gaining the knowledge necessary to be a leader. No matter your chosen branch, the point remains the same, you are there to lead the men and women that come after you.
From bias I say go Army, but go active duty. Reserves/National Guard are great, but when you make the military your life, your profession, and embody everything that goes along with it, you become a more diverse leader faster. Do your homework and know what you're getting into. Of course there is a lot of bullshit, but most of it you'll have to find out on your own and allow it to be a test of your personal fortitude. The Army will challenge you in a multitude of things and will force education down your throat. All they want you to do it follow when told, lead when your not, and gain the necessary tools to help yourself succeed and those around you at the same time.
For what it's worth, my family was against it but supportive. Four years later they will admit it was the best thing I ever did. Four years of service, got promoted every year (left the service as a Sergeant) and have a record of service I am proud of for only doing such a short time. In the words of Nike's motto for the last billion years, just do it.