Voted Pink Floyd - probably one of my all time favourite bands. However, I do think that King Crimson should have a place on the list - it's an amazing band, and their debut album "In the Court of the Crimson King" from '69 is in my opinion the best album ever made, and is generally regarded as the most influential progressive rock album ever.
All the options represent some really good music, though.
All the options represent some really good music, though.