CRF50 definately. The Suzuki and the Kawi are way underpowered Probably less than the powerwheels. The CRF has a throttle limiter and has plenty of room to grow and a key to keep junior out of trouble if you arent there to watch. Plus its a Honda. Just dont be suprised if you go back a couple of weeks later because they can be fun for big kids too. There are a couple of different types of training wheels to and I would reccomend the oned that attatch mid frame and not to the swing arm. They have a tendency to bend and come off.