Get the car that is most raced at your local track. That seems to always be safe.
Or, if you go with one of these brands, i don't think you can't go wrong.
Mugen
Team Losi
Associated
Kyosho
Ofna Jammin CR
I have seen all of these race and they are all competitive. I say cut 5 straws in different sizes, label each one with a name above, mix the straws up, close your eyes, and randomly pick one. Which ever one you pick, that will be the (Tr)Buggy to go with.