It really depends on what the kid wants to do. I would probably ask him what his preference is. It also depends on money of course. I would think that if he wants to race novice or something fun, get a Slash and he can drive it at home for fun also. If he plans on getting more serious, then get him a 1/10 scale Losi or AE, but they break easily and he could drive it at home, but it isn't the same as a slash. Is he mechanically inclined? That will play a big part also.
Otherwise his best option would honestly be a Caster fusion sport. I hate to beat the same drum, but it is electric so he would need extra parts to get it running, but with lipos and a charger, it is a no brainer on the charging, etc... No nitro to tune and mess with, and with 1/8 scale platform, there is a huge durability factor compared to 1/10 scale, so he won't be nickel and diming Mom to death every time at the track....and he can drive it at home as it is 4wd......