Which is the most physically demanding? (please list in order from most to least)
And also, which has the most racial/gender diversity?
Which is the most beneficial to my future in regards to finding a job and having life-long benefits?
What kind of job do you want?
Officer in the US Navy or Marine Corps: USNA
Officer in the US Army: USMA
Officer in the US Coast Guard: USCGA
Officer in the US Air Force: USAFA
The USMMA also has a service obligation, but there are several directions:
https://www.usmma.edu/after-graduation
Marines is most physically demanding and is the whitest and most male.
Your 3rd question begs clarification – as phrased, it’s useless. Like UCB said, what do you want to do? Each academy will prepare you to lead our nation’s service men and women in a time of pseudo war. To distill that into what your resume might look like in 10 or 15 years is a fool’s errand.
You should do some research on the degree programs at each of the schools, maybe seeing where the majority of graduates end up deciding upon. You want to be a nuclear engineer? Go to USNA. You want computer engineering? Maybe USAFA or USNA.
Frankly, you should trawl the academy forums – including the academy parents forum there: http://talk.collegeconfidential.com/u-s-service-academies/