If your after cars that you can get easy set ups & parts for at local clubs, the B4 & B44 ( and the .1's ) are the most common by far, followed by the Schumachers. Which is handy as all the Schumie drivers in particular have loads of spares for when their cars break
After that are the Losi 22's ( lots of those ) then Tamiyas & X6's. Im pretty sure im the only person running a Kyosho RB5 in the whole South Wales WRCA, and im not sure anyone else has a ZX5 either now, as i tend to run my TRF501x in 4wd ( which is by far the best 4wd...

). If you do run a Kyosho, im about the only local person who might have spares on hand. Unless i forget them, which i tend to do regulary...