We (most) always go to the Garden Grill and Crystal Palace.
We've alternated between Brown Derby, Sci-Fi, and 50's Prime Time, but the past two trips, we've eaten at 50's.
At Animal Kingdom, we'd always done Donald's Breakfastosaurus, but after a somewhat disappointing meal there, we haven't gone back. On our last trip, we tried Yak n Yeti and loved it, so I have a feeling we'll be going back.
As for resort restaurants, there are so many options, so we like to switch things up depending on where we're staying and what's convenient.