This is kinda a dumb debat, but, I love arguements
Everyone has there different opinions on the definition of a supercar or super truck for that matter so that put aside
The corvette "z06" is without a doubt "the best" performance car for the money. It is comfortable, outragous perfomance on level with many european cars costing hundreds of thousands more. Plus the electronics of the car, the sophistication of the ABS, traction control, ergonomics, and so on are worlds above others.
Second is the Viper, outstanding performance , but rough on its edges, still a great bargain for the money no doubt. But its level of sophistication is still in progress. But it wasnt developed like the vette. It was designed as a "race" car for the street. Very tight corners, tight suspension, tight driver space.
The two are both excellent cars , just in different sections of the automotive world. But hands down as a "street" driven car the vette is much more refined.The viper was developed to do one thing and one thing only do fast.
On the racing scene you can take a viper and go directly out and be competitive, the vette takes a little work.
Then you talk of the GT ford, well its in its own little world. For one it was a short production vehicle, so actually it should be taken out, but if not , then it is in the same league as the viper, to do one thing , go fast, nothing else.
All three of these cars are different catagories
The Z06 is a super street car capable of being a super car.
The Viper a street designed race Car
The GT a super car designed for the street.