Barto and Adami nailed it. No surprise there.
Specific to pizza, I can really enjoy and appreciate a lot of different styles. There is a fantastic Chicago style joint near my office that is some of the best pizza I have ever had. Very authentic, from what I'm told. But more importantly to me, very yummy. There is also a fantastic NY style place in my town, and a buddy of mine from NY says it is authentic and is the only place in the area where he will order pizza himself. But by the same token, I can also enjoy a pizza from the snack bar at Costco. All very different. But all yummy enough, so all good.
And Barto, I hear you on authentic foods. I have always been pretty adventurous and pretty open minded when it comes to trying foods, and learned very early on that we often have no clue when we label certain foods as belonging to a certain culture. I am regularly reminded of that fact whenever we invite people over for dinner and in response to my wife asking what they like, we get a response along the lines of, "Oh, can you make Chinese?" My Chinese-born wife then smiles, asks what specific dishes they have in mind, and simultaneously resigns herself, before even hearing the answer, to the fact that whatever common restaurant dishes they mention next will be nothing that anyone actually eats in China.
Having been to China myself, I can vouch for that. For the most part, the places where you can get the real, authentic Chinese food are the places where I am the only (or among very few) non-Chinese in the place and the menu is not written in English.