short course truck...combines decent ground clearance, decent handling, good durability all in one.
My fav is the team associated SC10rs. It is very tough, very well put together. The brushless system it comes with isn't the fastest thing out there, but will smoke anything you have owned in the past (especially with a 2s lipo)
These trucks are very tough, handle very well out of the box and take a lot of abuse. Ive owned 2 that I bought new...both wore out the tires before anything on the truck broke (that's about 5-7 hours of runtime!)

If you prefer traxxas, nothing wrong with a slash 2wd. A 4wd slash does have better traction, but I didn't like how it handled as much and the 4wd is more prone to wear/breaking. And since it is harder on the motor, it is geared a bit lower so it is not as fast as the 2wd (they use the same motor/esc)

Also, a SC10rs has a radio with throttle end points. This means you can have a 2s lipo in it and be doing 35mph...then just turn down 1 knob and limit the speed to around 12mph when you want to hand the remote to your kid. My son at 5yo learned to drive on my sc10. As he got better, I could gradually turn up the top speed. Now I let him drive it at about 75%. By next summer it may be safe to let him drive it at 100%.
Traxxas ESC's have a "training" mode...but that either gives you 50% or 100% throttle choices. With the throttle end point on the sc10's radio, you can go anywhere between 30% to 100%.