Having driven all these cars, I'd like to know what drugs you are smoking
The only car in that group that's in the same performance class as the Z is the cayman. I'm talking about the 09 Cayman too...
The S2000 is a great little car, but it doesn't have enough power to keep up with a stock Z, much less a modified one...or just about anything else but a Miata. The Mazda 3? competent? Hardly. The RX8 arguably can handle around a road course, but its not by any stretch of the imagination a good bang for the buck.
It's silly to think that after test driving the car and reading magazine articles you think you know enough or for some reason feel inclined to come post gibberish on a 370Z forum. I'd love you to drive my 370Z and still tell me after that your opinion still stands. In fact, lets take your precious Cayman and I'll take my Z to the track and see if you still think any of those cars you mentioned are still any good. Come on, I'll go with street tires.