I would think that there was already another thread on this
But if I had to pick ten. Most of mine of commercially successful but who cares.
By year
1. Blonde On Blonde - Bob Dylan
Shows the early period of jangly folk and introspective lyrics.
2. Disraeli Gears - Cream
The guitar driven psychedelic rock of the 60s
3. Let It Bleed - Rolling Stones
The blues - Hard Rock of the early period.
4. Selling England by the Pound - Genesis
Very nice progressive rock album.
5. Paranoid - Black Sabbath
Showing the hard rock of the 70s
6. Songs in the Key of Life - Stevie Wonder
Love this album, most optimistic album ever.
7. The Clash - The Clash
May be the best punk album. May be not. Buy it anyways, and make sure it's the UK version.
8. Debut - Bjork
Love it. Any of Bjorks stuff could be in this spot (except Homogenic and her sugarcube stuff).
9. Transmissions from the Satellite Heart - The Flaming Lips
Their commercial break through, they perfectly blended psychedelic distortion and pop melodies.
10. The Mollusk - Ween
Novelty Rock at it's best. Criminally underrated.
Wild Card: The Mad Cap Laughs - Syd Barrett
I only put it on because I am a fanboy and have yet to hear anything like it.