If you like very breakable plastic gears in your tranny then get a Traxxas. If you like a solid drivetrain with metal gears go with HPI. I don't care how fast it goes or how powerfull it is, if you have a weak drivetrain you will be spending lots of time fixing it. I have owned alot of different nitro rc's from traxxas, hpi, associated, duratrax, ofna, ect. and I can't complain one bit about the quality of HPI products. I can't say the same for traxxas.
There's my 2 cents.