I dunno, I change my mind all the time. As a kid, I thought the '70 Chevelle was my favorite muscle car. As a teenager, I thought the '66 Chevelle looked the best. Nowadays I think I like the '68 Chevelle the most. I always loved the styling of the 60s and 70s Cadillacs. I really like the weird looks of a couple 80s cars, like the DeLorean and the Countach. Some 90s cars, like the Viper and Supra, have a timeless design that will always look fantastic.
For a while I was obsessed with the Holden Coupe 60:
http://isthat.info/uploads/holden/holden-coupe-60-concept/holden-coupe-60-concept-11.jpg