Being a chubby person, I eat a lot of pizza.
Louie's is probably the best QSR pizza in the parks. Blows Disney's out of the water. I can easily say that, and leagues better than Kidzone, or Circus. I haven't had Via, mostly because I'm a poor kid, but I can attest for a lot of the places outside of the parks.
Giordano's and Flipper's are some of the best places to get pizza outside of the parks. Cici's is good since they have Universal and Disney Employee discounts. Other than that..meh. I also recommend Mellow Mushroom for the locals, there is one on Colonial. For the UCF kids, Lazy Moon has good and cheap pizza.