This is tough, but it would probably go something like this (in no order, and only one per artist, otherwise I'd probably only have Beatles/Stones/Floyd/Who):
Pink Floyd - The Wall: I'm a huge fan, and I know the purists likely won't agree, but this album resonates with me like few others.
The Who - Tommy: Another double album. Not as tight or focused as Who's Next, but the ideas are just spilling out from Townshend. Keith Moon is also on fire here.
The Beatles - Sgt Peppers: Obvious choice, but it really is an incredible album. A Day in The Life might be the best song ever.
David Bowie - Hunky Dory: Hard to pick one Bowie album, but this one is the best combination of style and substance (a balance Bowie has occasionally had trouble striking.)
The Rolling Stones - Exile on Main Street: Another double album! The Stones peaked with this one, and never came close again.
Neil Young - After The Gold Rush: Part Crazy Horse; part folk. A truly brilliant album, highlighted by the title track.
The Cars - The Cars: For me, the best debut album ever.
Elvis Costello - Armed Forces: Some of the best lyrics; great hooks.
The Rheostatics - Whale Music: Criminally underrated Canadian band. Doubt any of you will have heard of them. Check this album out.
Guns 'n' Roses - Appetite For Destructions: To think what could have been....