Go to your local track and see what everyone else is running. You don't want to be the only guy at your track with a particular car since it will be tough to find parts and set-up help.
As far as TC's go Mugen, Xray and Kyosho dominate the market and the races around here with an honorable mention to Serpent.
Sean. Certified speed crazed mowron.
Team Shepherd USA