For me, it is definitely now Skipper Canteen by the Jungle Cruise. My meal there was so outstanding last time I can't wait to go back again. I am even going to eat there twice my next trip. But of course you have to like that style of food.
Actually, I would say it's my fave place to eat now in Magic Kingdom - period. My meal there was definitely better than the ones I have had at Cinderella's Royal Table or Be Our Guest.
Otherwise, I have enjoyed meals at The Plaza and the Crystal Palace buffet quite a bit and Liberty Tree Tavern is pretty decent, too. The only truly bad one is, of course, the fake Italian at that Lady and the Tramp inspired eatery which makes Oliver Garden look like fine dining.