it really depends what you want - if your priority is characters, Cafe Mickey is your best option with kids who don't eat much, because you don't have to buy them meals, you can just buy pizzas to share between you all.
I love the Sunday brunch at the Steakhouse in the Village, this is a character buffet, its 33 euros per adult but only 8 euros per child, if you are there at 12noon there is a balloon animal maker there for the children too.
If you're not bothered about the kids (or you

) eating decent food, the character tea party at 4.30 at the Cowboy Cookout might suit - loads of pastries, puddings and sweets, and its around 15 euros per person.
And purely for the visual theme, I don't think you can beat the Agrabah Cafe - this is an attraction in its own right, absolutely beautiful restaurant with little rooms, representing the alleyways of Agrabah. It is a buffet restaurant, no characters, so maybe not what you're looking for with your children this time?