Music from the 70s is pretty awesome. I don't have in depth knowledge of it, but there is somepretty good rock and funk/soul from that time period.
I can really say much about the 60's There were a few good bands, but most of it doesn't seem to be my cup of tea.
And best bands of the period ? My current picks are Led Zepplina nd Queen, though I definitely would like to listen to some more Roxy Music and T. Rex before making any top x lists. (I really should do some more in depth listening before I can make a good list)