80c should have more "punch". Theoretically the 20c one can supply 100 Amps, and the 80c one 5.2*80 = 416 Amps. Probably not, but it will probably feel zippier with that one.
By the way, you can buy a "disposable" brushed motor to keep you running while you decide. A...
Good advice up there... I had a Torment as my first RC, the short course version of that chassis. In my opinion a decent 60A ESC is enough, it's a light truck.
My brushed ECX had plastic gears in the transmission, so I had to upgrade that soon after i went brushless.
They're decent trucks, on...