Beyond parts availability, Pro-4s and Cyclones are great for asphalt, and JRXS is good for carpet(based entirely on the length of suspension arms, I know either can be adapted to whatever surface you race on). TC4 is a good one too, great way to get into racing, is by picking up an RTR, and upgrading from there. But if you have experience with cars, I suggest a kit. Once you pick a brand, research the car to see the hits/misses, and go from there.