Best cat breed for kids is almost certainly the one that is not a pure breed but is a mix as mixed breeds have far better characters. Siamese and Persian cats, while being very elegant and all the rest of it tend to have very 'stand offish' characters so for kids stay clear of these.
The best way to get a kitten for your kids is if someone you know has a cat (with a nice character) who has just had kittens. Ask to see them and take your kids with you so that they can choose which one they like the best.
These kittens will have been born in a loving environment and accustomed to humans.
Having said all this you must be prepared to teach your new kitten 'right' and 'wrong' from the beginning. Any sign of a claw being shown and you have to reprimand it immediately so that he get's the idea fast!