We also went for the arts and sports and made our kids learn to swim 200 metres, so they would be able to survive if they fell from a boat. For DSs I would recommend a team sport, because, where I live, if they can't play they get left out at school lunch time. DS14 started football 3 years after his peers and had to work hard to be good at it. Besides enjoying the sport, he saw it as a way of making friends. DS11 was too uncoordinated to be good, but he now knows the basics, and can play if he wishes.
By far the most valuable EC activity is Speech and Drama. This has provided them with a wide range of fun group activities and skills, it has given them confidence, extension in English, and a record of exam results that has provided opportunities in acting, public speaking and leadership and will eventually give them a qualification. They both admit they have gained more from this activity than any other.
