For me it's a tough call between the 70s and 80s.
The 70s were full of innovation and top quality soul, funk, and R&B: Earth Wind and Fire, Marvin Gaye, Maze ft. Frankie Beverly, Stevie Wonder, P-Funk, Sly and the Family Stone, Mandrill, and so much more. :ahh:
But the 80s gave us Whitney...