The boundary between "great" and "not so great" is, of course, vague. In addition, the list has grown significantly, and now different albums have different degree of "greatness". Some are masterpieces, and most are not.
It must be mentioned that I'm not a fan of cheerful music, so such works are rare here. Moreover, classical music is almost absent from the list. Both due to my lack of experience of listening such music and due to the different classification of classical music (no albums in a common sense; composers and performers, so composing and recording years differ, etc.).
Experienced music listeners, of course, know the majority of these albums.
Updated on February 10, 2014. For the details and history of updates see this.
Aphex Twin1994 – Selected Ambient Works Volume IIBiosphere1997 – Substrata2000 – Cirque2002 – Shenzhou2004 – Autour De La LuneBohren & Der Club Of…