I am interested in joining the Army. What MOS would most benefit me during and after service?

So you need to look at it two ways. You are signing up for a long term commitment. The standard contract is 4 years active and 4 years inactive. That's an 8 year commitment. Pick an MOS you feel will fit your goals and interests. We don't know what you like or what checks your own personal boxes. IT and aviation have plenty of job opportunities post service but if you have zero interest in those things that wouldn't be a good fit for you.

First take “The ASVAB is a standardized test that reveals areas of strength and ability in science, math, and language. Taking the test is one of the first steps before you enlist.”
2. What is your preference for a job or your skills. If you are 18 or older what are your strengths, do you like health, electronics, office administration etc etc. Everyone is an 11B and the recruiter will try that MOS on your first contact this is for the Army.
Any branch, You are going to ask and they will offer is a negotiation. At the end is up to you. Some MOS offer bonus do you want to learn something for your future? Or you can take the bonus and shoot’s yourself in the foot. On these days of low recruiting numbers who know you may be offer what you want.
All branches of the military are good. Good luck to you.

What ever you do , like what that is first* And see if it the MOS has a civilian counter-part. My last 8 yrs in the Corp spent as a MP as I was a policer officer on e the outside. The very best of luck, be safe and be Blessed and pray for guidance.

To deliver advice beyond the obvious we need to know what your mid term/long term goals are.