Well, I'm going to suggest 2 meals. (I know you said 1....)
If only doing 1, I'd say Crystal Palace in Magic Kingdom - has Pooh, Tigger, Eeyore, and Piglet. It's harder to find the Pooh characters in the parks, although 1 or 2 can be found sometimes outside the Pooh ride. You can meet Mickey in all 4 parks (MK, AK, HS, Epcot), and Minnie is in at least MK and Epcot. Donald is in AK, I know. Mickey and Minnie are in seem to be harder to find in the parksAnd the food is very delicious, a buffet with many choices. For lunch and dinner, there's a large variety of cold salads, carved meats, and salmon plus some everyday stuff (pizza, nuggets, etc.). I think dinner has some additional items. And there's a breakfast too.