My son rides a burton protest 136. It's camber but I like camber so he didn't have much of a choice. He's been riding around 5 years and learned on a traditional camber board since day 1. I could be wrong, but I just kind of felt like he needed to learn on a board that forces you to use proper technique and will benefit him in the long run...now that he's built on that I will let him choose his next board, if he wants a looser feeling that you get from a rocker or hybrid camber or wants to venture a little more into the park, knowing he has the fundamentals to ride whatever he wants. Anyway, my two cents.
Also, you can get really good deals on kids boards and every brand seems to have 1 or 2 legit, high quality, boards for kids. They're also typically much lower in price. I got the Burton protest for 60% off at Altrec.