I've thought about this very question a bunch of times over the years, and several cars always seem to top the list:
1 - Buy back my '66 Corvair Monza coupe and treat her to the restoration she deserves
2 - 1966 or '67 Corvair Yenko Stinger Stage III
3 - 1965-69 Corvair Corsa/Monza convertible
4 - 1965 Evening Orchid Corvair Monza convertible with a Powerglide transmission (for my wife!)
5 - 1961-62 Corvair Station Wagon - Pro Touring (Hey, with a million bucks, it CAN be done!)
6 - A current model year Corvette Z-06 or it's equivalent (A guy's gotta have a daily driver that's under warranty, right?)
7 - Duesenberg SJ/SSJ
8 - 1969 Impala SS 427/4-speed convertible
9 - Monte Carlo SS Aerocoupe - Pro Touring (Family car #1)
10 - 1965 Chevelle 300 2-door Station Wagon - Pro Touring (Family car #2)
That's my list as of today. On some other day, some other cars might make the list: Lamborghini Miura SV, Ferrari "California Spyder" and "Daytona Spyder" come to mind right off the top!
(In addition to the Corvairs listed above, my dream Corvair collection includes at least one factory-restored, concours-level example of every year Corvair made, to include at least one example of every body style and model available - Let's say a 1960 Monza coupe, 1961 Lakewood 700 Station Wagon, 1962 Monza Spyder convertible, 1963 500 sedan, 1964 Monza Spyder coupe, 1965 Monza sedan, 1966 Corsa convertible, 1967 500 sedan, 1968 500 coupe, 1969 Monza convertible, 1961 Corvair 95 Rampside pickup, 1962 Corvair 95 panel van, 1963 Corvair 95 Loadside pickup, 1964 Corvair 95 Rampside pickup, 1965 Greenbrier Sport Wagon window van.)
CORVAIR: When you care enough to drive the vairy best!