It's hard.

. Many excellent albums. I forget something great.
Anyway, I'll try to write my list in no particular order.
The Jimi Hendrix Experience - Axis Bold As Love
The Jimi Hendrix Experience - Electric Ladyland
The Beatles - Sgt. Pepper's Lonely Hearts Club Band
The Beatles - White Album
John Mayall & The Bluesbreakers - Bluesbreakers with Eric Clapton
John Mayall - The Turning Point
Laura Nyro - Eli and the Thirteenth Confession
Laura Nyro - New York Tendaberry
The Grateful Dead - Live Dead
The Grateful Dead - Aoxomoxoa
Bob Dylan - Highway 61 Revisited
Nick Drake - Five Leaves Left
Tim Buckley - Blue Afternoon
Procol Harum - A Salty Dog
The Who - Tommy
Blood, Sweat & Tears - Blood, Sweat & Tears
Chicago - Chicago Transit Authority
The Electric Flag - A long Time Comin'
Jefferson Airplane - Surrealistic Pillow
The Velvet Underground - The Velvet Underground & Nico
Quicksilver Messenger Service - Happy Trails
Crosby Stills & Nash - Crosby Stills & Nash
Mad River - Mad River
Santana - Santana
Fairport Convention - Unhalfbricking
The Rolling Stones - Let It Bleed
The Byrds - Fifth Dimension
Mike Bloomfield/Al Kooper/Stephen Stills - Supersession.
Muddy Waters - Fathers and Sons
The Butterfield Blues Band - East-West.