Duncan's favorite fruit is a tough one, I don't usually feed fruits too often since they're so sugary, but I think he loves bananas best.
His favorite vegetable would be either carrots or spinach
He absolutely LOVES walnuts, and the two of us will often share one once a week or so
His favorite protein source is definitely Turkey, most of the thanksgiving leftovers went to him. However, being vegetarian, I don't have a whole lot of turkey in so I get more chicken for him and my dogs
His favorite chew is one of those "stick bundles" which pulls apart and throws all about his cage
Duncan's favorite toy is honestly, probably a cardboard box lol