Italy has a lot of forgettable pizza. The US has lots of truly awful pizza. Both places have great pizza of contrasting styles. (I'm a big fan of Chicago deep dish, for example.)

But the absolute best pizza I've had was in Italy hands down. The ingredients, preparation, oven, and expertise created one of the most amazing things I've ever eaten. I can't really say that about any American pizza I've had. There's a reason this pizzeria in Florence is packed every night and I've been turned away more than once, much to my chagrin.