When choosing a 'classic Tamiya', the poor old Super Champ often gets overlooked. It's not as well known as the Rough Rider or Sand Scorcher, but in many respects it really is a superior model, especially if you like to run your cars!
In essence it's quite similar to the RR and SS but has an improved rear suspension mechanism (which unlike the RR/SS actually works straight from the box!), a brass counter gear (nylon in the RR/SS), has hardened steel front suspension pivots (mild steel ones on the RR/SS), an improved (and adjustable) servo saver and a 'mechanism deck' which allows the battery to be removed with just one snap pin. This also makes it very easy to clean after a run!
They are relitavly cheap to run as the majority of the components are shared with the RR/SS, although rear bumpers are quite fragile if you reverse into something solid. The body shell can be fragile and are now quite hard to find in mint undamaged condition.
As is the way with classic Tamiya models, the prices are creeping up and up - buy one now while they are still affordable and you won't be dissapointed!