If I can comment about King Crimson, instead of @Fretless.
I can't imagine saying King Crimson did a rehash of their first album.
Robert Fripp, the guitarist and main songwriter, is truly progressive, changing for the better,
from album to album, and band name to band name.
I never owned "In the wake of Poseidon", but I'd look to see if Greg Lake is still the lead singer.
If you liked his voice, moving to a supergroup, Emerson, Lake and Palmer, he might be gone.
"Starless and Bible Black" was an interesting album, not sure what to call it.
Heavy mental?