I imagine the "best pizza" depends where you live, were brought up, and what you were exposed to over your life. I can't think of just one place to nominate as the best, so I will mention several that I thought were great and have made a lasting impression on my taste buds out of maybe a thousand or more that I've tried, as pizza has been one of my favorite foods.
Candlelight (northside of Chicago) makes a great real thin-crust pizza. You have to ask for it extra well done to get the tastier crispy version.
Vito's (Mesa, AZ) - great thin crust pizza from a family that moved from Chicago to Arizona and set up their fantastic restaurant in Mesa about 20 years ago.
Ed & Joe's (Tinley Park, IL) is another great thin-crust pizza place that's been around a long time and finally got recognized in Best of CitySearch as one of the top 10 best pizzas in the Chicago area. I had been going there for years before I left the area.
Aurelio's (Naples, FL) - a family from south suburban Chicago got a franchise from the small Chicago Aurelio's group of pizza places and opened one of the best pizza places in Florida down in Naples, FL. On most occasions, it excels and is actually better than it's parent restaurants up north.
Home Run Inn (Chicago) - truly one of the best pizzas of all time and it just won the Number One best pizza award in several sources, including Best of Citysearch 2006 for the Chicago area (actually tied with Lou Malnati's Pizzeria).
Fricano's (Grand Haven, MI) - makes an outstanding ultra wafer thin crust pizza. At this location, you don't have to ask for it well done to get it crispy as it always comes crispy and very tasty. In the summer there are lines out the door and they have no air conditioning in their restaurant! Amazing and unique place.
Paul's (Clearwater, FL) - superb thin crust pizza with some great flavor and spices. Just visited there last night.
Vito & Nick's (Chicago) - considered by Chicago "south siders" to be the King of thin crust pizzas. And it is fabulous.
Barnaby's (South Bend, IN) - don't laugh, this Barnaby's makes one of the best, flavorful thin crust pizzas in Indiana and is very popular with Notre Dame fans.
Lou Malnati's (Chicago) - The original one in Lincolnwood, IL makes the best deep dish pizzas in the world. Their other locations, though, are inconsistent and "hit and miss," especially their Wells St. location.
Charlie & Millie's (Seminole, FL) - a little dive with a handful of tables that makes an excellent thin crust pizza. Ask for it well done to assure crispiness.
Pizzeria Due's (and Uno's in Chicago) -- was one of the great deep dish pizzas ever, but that was back in the "good ole days." It's very different today, unfortunately.
Fox's Restaurant (Oak Lawn & Beverly, IL) -- one of the greatest thin crust pizzas I have ever had. It has a kind of Anise spice flavor to the pizza that makes it's taste extra unique.
Louisa's (Crestwood, IL) - fantastic pan pizza from a former cook at Pizzeria Due's. She quit her cooking job and opened her own restaurant about 15 years ago and it has been a phenomenal success ever since.
I'm sure that I missed some other good ones, but there's always another day.