I would say Corvette will be less forgiving for your mistakes, I also don't like the quality of the car (interior is like 10 years old, terrible seats, automatic transmission is said to be worst than DCT). On the other hand, if you are looking for a weekend car/track car, might give you the best fun. Never driven Porsche. And M3 was the choice for me when deciding between C6 and M3 since I needed it as a DD.
What I would consider:
- attention the car will get, do you want more or less?
- cost of ownership
- how you will use the car (you won't be able to drive Vette in snow)
- the rest is about how much you like the design and maybe how you feel when driving it. I kind of don't believe in test drives though because if you don't have like 10 years of sport cars behind you, all 3 of them will make you grin from start to stop and it will be hard for you to say which one "handles better, makes you more connected etc.". At least I wasn't able to say...
btw, why Z06 and not C6?