As an old-timer martial artist, I would say go with the Brazilian JJ class first. These days, I see a lot of people train in hybrid mixed-martial art systems, and while they tend to learn a large spectrum of techniques, they never "master" any particular technique or skill set.
The key to effective self-defense and personal development is training techniques until they become unconscious reflex patterns originating in the lower brain and spinal cord. If you have to "think" about your technique in a real world situation, you are already too late. Your son is much more likely to develop his technique to this level in a more traditional martial art class like BJJ, than in the CSW class IMO.
Having said this, the most important thing that you could do as his parent is let him choose the class to take. Whatever he chooses, he should really be excited about learning it if he is going to get something from it. You will know that he is on the right path when he is practicing his techniques while being a couch potato, lol (but seriously).
The best thing that I have from gained from my martial arts training over the years is the many life-long friends that I have made from it. I still have two good friends from my first training in Karate over 35 years ago, when I was just 7 years old. We are all old and fat now, but our friendships remain strong.