i never really got into gto's until around 2004. me personally i think the spoilerless 06 gtos are the better looking with the blacked out lights and split duals. my next favorite is the spoilerless hoodscoopless 04s. now seeing the way i do like cars i'd say the 64 through 68 just because i liked the novas of those years and that boxy body style. from 72 to about 75-76 cars sucked.
Love the 1970 because my folks had one.
I do love my 2006, though. Ton o' fun.
Also, I love all those frame-off restorations people have done. Good god, most look better than when they were on the showroom floor!