This is a loaded question. Depends on how you define "good."
I dont think little kids should be around them at all, especially if you have roosters.
Once a kid gets up enough to be around them, then it doesnt matter what the bird.
Others want a cuddly ball of fluff that wont do more than sit there, so the kids can handle it, pull it's feathers and so on.
But, since these are rather large, quirky birds that do unexpected things, at times, the answer is somewhere in between. We're not talking happy little bunnies here. These are chickens, a veritable force of nature. Be prepared for anything, thats all I'm saying.
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Silkies are probably your best choice.
Other breeds that are often recommended as docile are RIR's, Barred Rocks, Brahmas, Australorps.
But this is very subjective and there are hardly any absolutes.