I'll buy Pink Floyd for a dollar. I do not agree with King Crimson, though. The first two albums I like very much, and the first is a classic.
Deep Purple missed it by THAT MUCH, unless you count the live Concerto album; I love all that stuff because I'm a Blackmore fanatic, but it doesn't hold a candle to In Rock through Stormbringer.
One could argue that the Beatles and the Rolling Stones fall into this category, unless you prefer the early albums, heavy with covers of classics and standards.