Jiujutsu is great if you want to defend against one opponent. But, if it’s for your kids, it all depends on the teacher. The questions you should ask yourself is:
1. Do you want you kids to be able to defend themselves, and eventually those around them?
2. Do you want them to learn manners and self-discipline?
3. Do you want them to compete in tournaments?
In my experience, tournament fighting is counter-productive to real self-defense. You’ll get some ability to defend yourself, but a true warrior martial art will not focus on tournaments.