When I was in the States as a kid (30 years ago) it was always Pizza Hut. I wasn't all that struck on Domino's or Papa Johns, although I think the latter was horrendous. I guess that's why the NY Rangers give away their free pizza every time they score
There was another lot I used to get pizza from - a company called Sbarro's. I don't know if they are still going these days, or even if they haven't been mentioned here,I guess they must be pretty crap. But back then they used to do good pepperoni, spaghetti, and the calzones as far as I can remember.