I really prefer dinner at Chef Mickey's. But we are not morning people or big breakfast eaters in my family so I am biased! We have done breakfast and enjoyed it but just fine that dinner suits us better. You can't go wrong with either, but if you aren't too keen on breakfast having dinner then heading over to the MK for Spectro and Wishes is a great Disney evening.
At breakfast they have the standard eggs, bacon, sausage, breakfast potatoes, fruit, oatmeal, muffins, danish, donuts, Mickey waffles, pancakes and probably a bunch of stuff I cannot think of.
At dinner, they have a nice salad bar with fruit, cheese and peel and eat shrimp. They have a kids buffet with chicken nuggets, pizza, mac and cheese, french fries etc. On the regular buffet, they always have one or two carved meats, a seafood item (usually salmon), mashed potatoes, usually a pasta, vegetables, and lots more. They also have a nice dessert bar with some nice selections and build your own sundaes.
Chef Micey's is so much fun, your son will love it!
P.S. You will love SSR, its our home resort too and we love it!