As I understood it, anything more than 25 years old is an antique. At least, that's the boundaries for putting such plates on cars here. That includes anything that I read about in high school, which means we could discuss Cordobas, T-Birds from the late '70s, or, my favorite from that time, the 2 door Caprice from '77 to '79. After the '74 to '76 models, it was a breath of fresh air.
I have a hard time defining anything as a favorite. I admit to fairly broad tastes, though, when we get to this, that first choice is usually American. I liked GM cars from the 60's but not the GTOs and such. Two of my favorites would be the Impala SS from '67 and '68, and the Corvair Corsa.