One of the absolute best and most obscure albums from the 70s is McDonald and Giles, from King Crimson. They went off did their own thing, and it is sublime perfection, truly a gem. It's like King Crimson but much softer... like if the Beatles went prog. I recommend just listening to the whole thing.
I've been convinced of The Who's place in the pantheon of rock and roll genius ever sine I saw Tommy.