Grand Floridian and Animal Kingdom are my favorites! I know they're two completely different experiences, but those are the two I used to stay at the most as a kid and I have a soft spot for them. Nothing beats walking into the Jambo House lobby!
Hmmm....I love going to resorts and just visiting. The atmospheres are so unique and it's a really nice break from the fast pace of the parks. The theming of these are unique as previously stated, so comparing them on that level (to me at least) is like comparing apples to oranges. And of course, I can't choose just one. So I'll give my picks for different categories.
Food: Beach Club/Boardwalk, Poly, Wilderness Lodge (Artist Point is really good!), Port Orleans duo, AKL
Location: Beach Club/Boardwalk (Epcot is literal steps away), Poly, Grand Floridian
Aesthetic/ Theming: AKL, Poly, Beach & Board, Grand Floridian
I have to give honorable mentions to Pop Century and Art of Animation as value resorts. Pop's remodel looks great and the theming of Animation is, in my opinion, sorely underrated.