Nismo because the cost to maintenance a Porsche will probably be 4 times more.
Before buying the 370z I had a Mercedes, and oil change on the C320 cost 3 times more than that of the 370z. I would have to think oil change on a Porsche 911 has to cost a lot more than a MB C320.
But if money is no object then go for the 911. GL with your decision
