I like pizza crust that is good enough to eat on its own, so my favorite pizzas so far have been from Bonci's in Rome, a crispy potato pizza from a bakery in Trastevere, and several pizzas in towns in Puglia that had their crusts made from ancient grains. My preference would be never greasy, never wet in the middle, never very cheesy. Not fond of any meat on pizza.
Had several really good pizzas in Florence, too, all pretty far from the main tourist areas. I did enjoy the classic pizza from some of the classic places in Naples, plus one street-food pizza in Naples that was deep-fried and hardly even pizza anymore but really good.
There are so many regional pizza-like things in Italy that are really excellent, like a piadina in Emilia-Romagna.
There is now a Bonci pizzeria just off highway 90 in Chicago, so on our frequent driving trips from Minnesota to New York we now schedule our driving so that we can stop there and eat pizza for lunch both ways. Last year we even greedily bought two extra boxes full of different pizzas on our way home and then accidentally left them in a motel refrigerator in Wisconsin and almost wept.
Pizza is absolutely one of those foods that there is no "best" of and there is no "real" pizza, just what is your favorite style. I've never had mediocre pizza in Italy, but then we are very careful not to go to mediocre pizza places and not to order it at regular restaurants whose specialty is not pizza.