I always find it funny when people claim that the rise of Nirvana and grunge in 1991 made rock dominent again and killed off cheesy pop music. Not so long ago I was looking at the list of Irish number one singles in 1992, 1993 and 1994 and you had artists like Snap!, Wet Wet Wet, Right Said Fred, 2 Unlimited and Whigfield dominating the charts
I think the really innovative albums of 1991 were outside the realms of hard rock and metal.
My Bloody Valentine - Loveless
Massive Attack - Blue Lines
Slint - Spiderland
Primal Scream - Screamadelica
Talk Talk - Laughing Stock