For which school does he feel the best fit? If he’s in a college environment that he likes and thrives in, he should do well at the ROTC detachment, regardless of size.
One of the first military skills essential to a junior officer is understanding he will probably never have 100% of the information he would like to make the perfect decision. Many times he will have only 60%, or less, and he’ll have to go with gut and the best case he can make with what he has, and just get on with it. Delaying a decision is also making a decision.
Which school has majors areas that appeal? Class sizes that seem right? Which school has the culture that appeals? Which school and unit did he have his best conversations with? Which school will he most regret not going to down the road?
He knows the answer. It’s hard to let the other one go and close a door in one of his first major adult decisions.
Another military rule of thumb is roughly 30% of a unit’s staff changes every year. That means the culture and focus within a unit can change too.
He is fortunate to have two solid choices. Time to identify the top two or three factors that matter the most to him, determine which school and unit have the best match, make the decision, and get unstuck.