Agree with this so much! The education and opportunities are important. The social development and spiritual maturity that happens is equally valuable.

This can happen at all of the choices you listed. It will be very different at different schools.

Much of the college social scene at non-LDS schools revolves around drinking alcohol, so your son will need to be prepared to either (1) be the designated driver and learn to enjoy that scene or (2) find a group that doesn't center around alcohol. A high school girlfriend of mine who chose not to drink until 21 was always the designated driver in her friend group - it can be fun at times but got old for her. Option #2 will limit the people he may be close with, but isn't a deal-killer for the right personalities.

For me, I will suggest my kids do undergrad at an LDS school and to do grad school at a non-LDS school. Those undergrad years are so influencial in which path a person follows in their lives.

Again, I'm not saying that BYU guarantees one thing and non-religious guarantees another, I just think there are more options that lead to the path I want my kids to follow in an LDS college.