Did you get a lemon or something? Seriously, you take every opportunity to bash the hell out of the car. Mines been a great car for 3 years now. I'm not sure if your just GM biased, kidding around, or if you really did have a lemon. Just curious.
Wease, to answer your question, I would go with a C5 Z06. I don't think the C6's are as fast as the C5 Z06's. The C6 I raced last year when I just had the pulley and chip didn't put up much of a fight. I'm certain a C5 Z06 would have fared better. The Vettes have better build quality than the Cobra and are more balanced overall. If my wife didn't have a hangup about two seaters I'd have a C6 Z06 sitting in the garage right now. If you just want a muscle car that can make 600RWHP pretty easily, then the Cobra may be the way to go. I've been very happy mine and it's been a great car.