A tough one!
I'd consider one of a) Corvette Z06, b) BMW M3, or c) Porsche Cayman, or d) GT500Supersnake.
Practicality wise, it would probably be the M3 as its the most well rounded car -- track, cruising, or going with the wife to the Opera and it still works.
Porsche supposedly make the most fun to drive cars. As pure a driving experience as there is.
A shelby mustang is iconic.
But in my heart of hearts, and i think this is universal...everyone wants to own a corvette at least once in their lives -- even if they're not willing to admit it.
