All the options mentioned above TKD, Karate, BJJ, etc... are just various parents experiences and what worked for their kids. I don't think anyone is suggesting that one particular style or location will address the needs of all kids.
We looked at all the above before deciding so I think if your kid hates karate, tkd, or bjj you may want them to try something else. But I think most parents take into account that kids have to like it to continue it.
There are a lot of factors on what activity is suitable for a particular kid at a particular location. You may like how the instructor is at one school but not another. Some schools may be very meticulous in keeping it clean others not so much. Your child may click with the group of kids at one school but not another so definitely explore the other facets of a school beyond just the type of martial art as it can make a big difference on their experience.