Just reading through this thread, sweet Jesus 1991 was an awesome year for music, here's my Top 8, and all eight I would consider classics...
In no order (impossible to seperate them)
Soundgarden-Badmotorfinger
Pearl Jam-Ten
Nirvana-Never Mind
RHCP-Blood, Sugar, Sex, Magic
Guns N Roses-Use Your Illusion 1+2
REM-Out Of Time
U2-Achtung Baby