Vette's have been the king of the hill for a LONG time. Bang for buck, nothing beats them.
The C6 Z0 is more impressive, IMO, than the ZR1, for what it is. The only deciding factor on me picking the GTS over a 05-07 C6 was the forged motor. I didn't want to build another motor. With the turbo's I should be able to hang with the local crew no problem, even on bottle the car did pretty well.
Corvette and Viper owners (being a GM guy myself) are like distant cousins, they are always in competition, both think they are superior, and deep down, they respect each other. I've witnessed, more than once, 08 600HP Vipers being pulled by BONE STOCK C6 Z06's by a car or 2, and the Viper was out by a car on the hit. It's classic power to weight.