I don´t agree that Go! are junk. It is a matter of how many time you are willing to spend making them better.
Of course they need a lot of tuning, especially regarding the bad aesthetics caused by their huge wheels.
I think Lloyd will send you info about motors. But it is the same - try different ones to find out what fits your needs best.
SCX compact are the best models straight from the box.
Diy cars are of course much better . The earlier you start scratchbuilding the more fun you will have with the hobby and this scale.