One of the first things you need to consider when choosing a car is local support of the vehicle. If you can't buy parts at the track or local hobby shop, you will need to order your own stash of parts to have on hand. The other part of that support is the number of local racers that use that car. Having a local base of people familiar with a car will definitely help you get it set up on race day.
Personally, of the cars you listed the only one I've driven is the FTTC3. Absolutely awsome car, and it's easy to get it set up. If you are going to race stock, this will be the car to have. It works great in modified too, but in mod all cars seem to be on a more equal footing. The shaft drive and the free drive train of the TC3 will allow you to get the most horsepower from a stock motor. As far as being fragile, this isn't the issue many make it out to be. I use the BRP nerf wings to protect the rear A-arms and the RPM front bumper to protect the front and have had minimal breakage.
I've raced against the Xray and it is a very competent car in the right hands. It is a bit on the expensive side, but it is definitely a quality car. Like other belt cars, to be fast in stock, these must be driven very smooth.
Jeff Gilligan