In The Court Of The Crimson King definitely is their best... imo anyway... but aside from the ones already listed, I think that In The Wake Of Poseidon is a pretty good album too! I gotta get Discipline...
King Crimson have four distinct eras.. 1969-1972 is very 'airy', very classically influenced, lots of jazz instruments (flutes, brass sections, etc), the most 'hippie' of their periods.. not very rock 1972-1974 is hard rock, almost heavy metal, mixed with free-jazz improv sensibilities/atonal violin playing 1981-1984 is quirky new-wave with ambient influences, think a more heady and accomplished Remain In Light Talking Heads 1995-2005 mixes the hard rock of the classic 70s period with the quirkiness of the 80s.. very heavy on improv I'd recommend In the Court first.. if you're attached to that sound, continue with the next three albums.. If you're curious about their periods, get Larks Tongues In Aspic and Red (from the 70s period), followed by Discipline and THRAK
i got "in the court of king crimson" and "Starless, and Bible Black", these two i know are very good albums. havent heard anything else from them yet.
I recommand you to check in the best web-site about progressive rock bands: www.progarchives.com You can download free MP3 and you'll have idea about how Cing Crimson sound!
"In the Court of Crimson King"(69) ...bla bla bla ...it lacks of originality ...but it's the truth... it's their only classic album... mmmh but someone told me to listen to their "Red"(74) album ...it's probably their second best long player (i heard say here and there)...and it's the only one of their 70's album that i don't own...
my favourites are (in order) Starless & Bible Black, In the Wake of Poseidon, Larks' Tongues in Aspic, Red, and In the Court of the Crimson King. i haven't listened to these guys in months.. thanks for reminding me. :H