Mid to late 60's. Most of the 70's And a couple here and there of the 80's
Yah, it would appear a lot of us are focusing on the 60's and 70's because that's when most of us here were honing our chops, but the 60's and 70's stand out musically for other reasons. Let me throw this out for argument....
No other decades since the 60's and 70's saw such a wide range of Rock diversity and Pop evolution.
Deansdrums paints a good picture of 1964, but look at the evolution of pop music from 1960 to 1969. We enter the 60's with Elvis, the Everly Bros, Chubby Checker, Sam Cooke, and the Ventures, and we leave the decade with the Summer of Love and Woodstock; Hendrix, The Who, Stones, Black Sabbath, Cream. Huge difference going out of the decade than coming in.
And the 70's saw heavy hitters Led Zeppelin, Deep Purple, Aerosmith, Alice Cooper, Queen and AC/DC playing concurrently with Disco, Punk, and Funk. What other subsequent decades have demonstrated such diversity and changes in Rock? Sure, Jazz and Folk thrived continuously through all the decades as the quiet relatives sitting at the far end of the Thanksgiving table, but as far as Rock goes, I just don't see anything revolutionary or innovative happening after 1980.
Soap Box
Now let loose your arrows of disagreement.
Mike