Disney Springs has a lot of great places that you can do with the flow. Polite Pig is great. Blaze pizza is a good standby if you can't get a sit down reservation on the spot.
In the parks, my wife loves Tot-chos at Woody's Lunch Box. (I'm not as big a fan. Give me tots OR nachos. But, not both together.) For breakfast, the cinnamon roll at Gaston's is good.
If you're into hot dogs wrapped in a pickle and then deep fried, there's always Blue Ribbon on the Boardwalk.
We normally do at least one sit down ADR per day, so I don't have experience with going with the flow for those. But, the ones above are the QS places that we hit when we feel like it.