There are three main players. Losi XXX-CR, AE B4 and Kyosho RB5.
The RB5 is the most expensive and as has already been stated parts can be hard to find and are expensive. Car handles great and has proven durable.
The B4 is a great handing car but I would say is the least durable for the average club racer. I have seen a lot of parts broken from front towers, to chassis on this car. Parts are cheap and easy to find though. Shocks are the worst. They are smooth but require very freqent rebuilding
The Losi is a good strong car. Parts might be a little harder to find depending on your area but should be much easier to find then kyosho parts in most places. The losi is a very durable with parts being cheaper like the B4. The team guys have been using some older parts on the car which means some extra investment (~$20) to run "team setups". Shocks are good with far less frequent rebuilding then the AE shocks.
All three cars are very competative. All will get you in the winners circle.