If you go in parks, I'd say it's Three Broomsticks in IoA and Simpsons in USF. Big restaurants, always busy, tons of turnover.
As for CityWalk... I don't know. The real money is in alcohol. One of the older bars might take the prize. Cowfish is relatively small (?) given it's popularity. I'd be shocked if Toothsome didn't take crown in 6-12 months time. It's big, seems busy, and will hopefully have fast service soon.