Contemporary
I voted for the Contemporary - I absolutely love California Grill, hear great things about the Wave (will try it my next visit), think that the monorail access is fantastic, and like that its, well, 'contemporary'. The fact that I first stayed there in '74 may also be a factor ....
The Animal Kingdom Lodge was a very close second for me - I love Jiko and Boma, the lobby, the savanna views, etc., but don't think that the rooms quite measure up - and it is quite 'off the beaten path', meaning long bus rides or driving to the parks.
Yacht & Beach Club is very pretty, and access to EPCOT via the International Gateway is so cool (particularly during the Wine & Food Festival) but I don't enjoy the dining there as much, nor do I find the theme as immersive.
It has been a long time since I've stayed at the Polynesian - though I did visit back in November - its very pretty, but just is not #1 for me.