This is a tough question because I've always put a lot of thought into the cars I buy. I like 'em all, really.
But, #1 may have been my '69 Triumph GT6, bought it in 1971 just after HS graduation. I did key mods to the engine and suspension, so she would fly. She went everywhere with me including 2 trips down A1A VA to Miami and the Keys, plus I autocrossed and raced her (successfully), too. Great car for a young whippersnapper.
A close second was an '86 BMW 325ES that I bought in '87, the model with the leather Recaro seats and premium stereo. I loved every moment of driving her, a real driver's car. Verrrry smooth, powerful, pretty. A real chick magnet, too.
Then there was the '68 Z-28, and the '70 Mustang, and the Mini Cooper, and . . .