Although it’s not the standard numerical concept of a decade, my favorite is probably 1967–1977, although I guess it could be said that rounds up to the 70’s. ;-)
1967 is when the Cream and Jimi Hendrix released their first albums.
Their arrival signified the emergence of comparatively advanced musicianship, the most notable of which for me was the guitar work of Clapton and Hendrix.
In 1968, another English-bred guitar great, Alvin Lee of Ten Years After, arrived and Hendrix released his third excellent album, “Electric Ladyland”.
I think it was in that year two other legends, Rod Stewart and Jeff Beck, released their first album together: “Truth”.
In 1969, Led Zeppelin and Santana released their first albums, and Zep also released their second album.
In summation, I’d say the primary reason for the excellence of 60’s music was the massive influx of English artists.
It could be that in turn inspired the emergence of more intelligent, creatively advanced, and aspiring American music in the 70’s.
In the early 1970’s, America’s best rock guitarist, Johnny Winter, released my favorite rock album, “Johnny Winter And Live”.
IMO, it was in the 70’s that Santana released his best music.
It was also in the 70’s that I was introduced to the artistry of Steely Dan; the Eagles; Crosby, Stills, Nash, and Young; and Fleetwood Mac.