Given a choice and availability, my personal preference is the flours from the King Arthur Company, including their all-purpose flour, bread flour and the high-gluten Sir Lancelot flour (KASL). The KA flours generally have higher protein levels than competing brands and they are unbleached, unbromated and milled to very tight specs. I have tried a few other brands of high-gluten flour and thought that the KASL was better overall. But I have never done a blind test to see if my biases played a role in my perceived preferences. I thought the All-Trumps high-gluten flour was good, however, and would be my first choice after the KASL for a high-gluten flour. For deep-dish purposes, I use mainly the KA all-purpose flour. I usually use the KA bread flour when I cannot get the KASL.
I know that for the Chicago deep-dish style, buzz prefers the Ceresota brand of all-purpose flour, which is a regional brand available in the mid-west. Another regional brand that seems to get high marks is the Stone-Buhr flour, which is a relatively high-protein flour available in the Northwest. The flours from Giusto's, which is based in the San Francisco area, are also of high quality, but I would personally rank them a bit below the comparable KA flours I have tried. Again, my biases may be showing.
We all have our favorites, and they differ from one person to another, so my best advice is to try out different flours, including supermarket brands, to see which one works best for you. In some cases, your choices will be dictated by where you live and what may be available to you locally and also by what you are willing to pay, considering the high cost to ship flour across the country. In due course, if you are anything like me you are likely to end up using different flours for different dough recipes and different pizza styles.