I've only ever stayed at the Polynesian but I've seen the others.
I would have to say the Boardwalk, Yacht Club, and Floridian are my favorites. I love their clean, early era style and all of them are located by the water.
The Polynesian, Wilderness Lodge, and Port Orleans Riverside make very close seconds. Coronado Springs probably comes in around third.
I'm interested to hear your opinions.