My DS received an AROTC 4-year scholarship and accepted to VMI. He loves the idea of going to VMI, HOWEVER, he knows how prestigious getting into the USNA is. Besides the pros and cons of each school, what would be the pros and cons of being in the Army vs Navy?
Your last question is massive. Two different missions, two different cultures, both fine ways to go. One does its work mostly on land, the other at sea. Both go in harm’s way. Both can take their members halfway across the world for long periods of time. Both emphasize leadership, though it’s exercised in different settings.
I assume your son has done the research on various officer specialties, and has found some of those appealing. Some realize being at sea/under the sea/in the air is not for them. Some realize being in the dirt/sand/scrub/desert/mountains is not for them. The four years at an SA or ROTC program are the steppingstones to a minimum 5 years in uniform. That should be your DS’ focus.
VMI is a fine way to go, and if that culture feels right for him, that’s a good thing.
Down the road, no one really cares where the commission came from - it’s all about performance in the assigned job. The SAs do a superb job of preparing future officers by immersing them in military culture and exposing them to a wide variety of professional experiences, as well as providing a lifelong bonding experience like no other. ROTC programs also deliver good officers, no dummies, who quickly catch up on the professional stuff the SA grads lived with for 4 years. I would guess the SMCs also create strong bonds in their classes. Quality floats to the top, regardless of commissioning source.
Once your DS decides what Service he feels is the best fit, he can work backwards to the path that is the best fit. Then embrace his decision.