You're clearly intentionally snubbing the obvious great bands in that time period (Led Zeppelin, Black Sabbath, Pink Floyd, David Bowie, etc.), so I won't go into those.
But how about some you might be less aware of?
Hawkwind, Flower Travellin' Band, Camel
I guess I can see you mistakenly overlooking Joy Division's Unknown Pleasures because it's easy to think of it as an 80's album.