What type of traxxas rc truck is right for me?

Im looking for an rc that runs on a battery pack, not gas. i want it to go around 40 mph. i want to be able to go fast and be stable, but go over off road obstacles and climb hills. i wanted to get the stampede up first but was convinced that they are not as stable as the revo or slash. pleas help. oh yea i also want to know if a 1 wheel wheely bar is more stable than a 2 wheel one?