Go to your local track and see what is popular. You will probably find far more TC racing going on then 1/8th. Chances are they will be running Mugen MTX-4R's, X-ray NT-1's and Kyosho V1RRRRRRRR Evo 53 whatever's. Pick the one you like the best and can get parts and support for.
If you actually have a local 1/8th scene going on I would go with the Mugen with some type of Novarossi based motor. In off road there are a lot of cheaper motors that work great but no one can touch a Novarossi rod for onroad abuse. If you go with something else, change rods after break-in and at least every gallon after that.