My second favourite Prog band behind Pink Floyd is Genesis. I don't mind their Pop era but Calling All Stations is a horrid attempt at trying to return to Prog. Parts of their 80's work wasn't that great but compared to there swansong they look a lot better.
On a lighter note their early albums especially Selling England are pretty spectacular! Definitely a band you should have a look at if you have any interest at all in Prog.