Well honestly, if you're just going to have fun with it then it doesn't really matter. Parts availability should probably be the most important factor. So maybe like an associated TC3 or 4 or something like that which won't be too expensive even second hand. Check your local hobby shop and see if they have parts support for any onroads then go shopping. See what you can find over at RCTech. There's always a boatload of stuff for sale. I can't imagine you wouldn't be able to piece together a brushless onroad for a modest amount of cash. Look for people trying to sell rigs as a basis for a VTA car. VTA class generally sees a fair amount of older chassis', so people with older touring cars looking to sell use that as a sort of marketing tool.
Personally, I race a pair of JRX-S Type R's which Losi doesn't even sell anymore, but parts are still readily available.
