If you aren't racing at all my first choice of car every time would be a TT01. Nothing takes a beating like a TT01, if you have an accident hard enough to break the rear suspension of a TT01 the same accident would damage any other car, with repair costs being greater most times as well. I would also recommend staying with the Tamiya plastic suspension arms, in an accident the arms flex to absorb the impact and then spring back. Alloy arms will either transfer all the shock loads directly into the chassis, so you end up breaking the chassis every time, or in an accident that would cause the plastic arms to flex and then bend back, with alloy arms the alloy bends and stays bent, so your alloy arms have to be replaced regularly.
Don't even think about the 3Racing Sakura or SpecR S1 that have been recommended above. Apart from having very few shops worldwide stocking spares, the drive belts will quickly get chewed up by the dirt and grit on the road. The TA06 also has exposed drive belts, and like the others the stiffer plastics used are much more likely to break in any accident that a TT01 will flex and bounce off.
We run events where we hire out r/c cars to the general public, so the cars have to withstand being driven into track barriers and each other, running constantly for up to 8 hours a day by people who don't have any driving skill. We use TT01s because they are proven to withstand that abuse with very few breakages.
If you want to start racing, again the best car to start with is the TT01 you have. It works, there isn't much you can tune on it so you can't mess up suspension settings making it difficult to drive on the track, and you can see what the other drivers are using so you will have a better informed choice of what car to upgrade to if you want to stick to racing.