I did air cadets, had no interest in planes but my friends did it. My experiences through cadets completely shaped who I am today. I flew planes and gliders, I had friends with their Pilots license before they had their drivers licence. Yes there is drill but that is no bad thing, it teaches order and following instructions and gives those giving the commands a chance to lead and build confidence. I learnt to shoot a rifle which teaches you how to respect equipment. I've roughed it in tents with no gadgets (not that there were many in the early 00s).
I did camps in the UK and overseas, I did adventurous activities camps and went on to becomee an outdoor activity instructor for a while.
It gave me lots of experience to pull on for interviews and my personal statement. I learnt first aid really robustly (not just a 3 day course) and won first aid competitions and have put that in to practice in the real world many times.
We took part in sports competitions in swimming and athletics, Doe.
Whilst many cadets go on to join the air force, most of my friends from cadets are public servicely minded and work for the Police, fire and rescue, paramedics and Environment Agency as they loved the outdoors aspect. Those who really loved planes went on to become pilots and engineers.
Any cadet group will teach your child great skills and give them great opportunity's in any of the services you need to find the right one for your child as each has their own ethos and culture. I think air cadets is fantastic for quieter and introverted teens but arrange to visit a couple and see which your child likes best.