it's not an easy question. It's subjective. You'll get so many different answers. No answers are right or wrong. And, people can only comment on resorts they have actually stayed in. We've stayed at CR, Poly, GF, CBR, CSR, WL, POR, Swan, Dolphin, YC, BC, All Star Music, and OKW.
I think WL is over-rated. Many people would not agree. We weren't impressed with the small, dark rooms or the small pool or the CM's. However, the lobby and grounds and outside of the hotel are breathtaking. We didn't like the boat transportation. SLOOOOOOOWWWWW.
We didn't like OKW - but I don't think it gets tons of "props" on the boards anyway.
As far as under rated - my vote would be for the Swan and Dolphin. They get a little bit of flack for not being Disney owned. We were a bit apprehensive about staying there for the first time in 2004. Boy were we pleasantly surprised! We didn't miss a bit of the magic - it has the magic and then some.
Again, this is all a matter of opinion. But it's good to read about the different points of view.
PamNC