The quality of the ingredients is very important. I have scoured the lands, trying every brand of flour, tomato and cheese I could find. I've had cheese flown in, paying $75 for enough cheese for just one round of pies, I've even made my own cheese from scratch, starting with just milk. I've tasted every brand of tomato I could find and peeled and blanched my own from local tomato growers. And theses things do make a difference. But there's just no getting around the simple truth of 'the big three' - High heat, good natural yeast, and mixing technique. Getting these right will cover a lot of sins and getting these wrong will screw up the best ingredients.
Varasano even praises and ranks other pizzerias and gives directions to them! Link -via reddit