I have a very nice stones that I purchased some years ago that has served me very well. It's made by Primo and is a big heavy stone. The thermal mass it has convinced me to buy it as well as the opinions of other Primo owners who had used it.
I have two very good friends who just had to have the steel mentioned in Duke's post. These guys also had the Primo stone. My buddies swear the baking steel produces the world best pizza! And these guys are very serious pizza affecianados.
Good crust comes down to having a lot of thermal mass under it. Thats why HankB's post is so very interesting ... those firebrick have a ton of thermal mass. That's a very cost effective way to cook very good pizza. It's essentially the floor of a dedicated pizza oven!
As for me, I think I'll stick with my Primo stone for now. When I futz things up and drop it, I'm certain I'll be buying the Baking Steel.
Here's to great cooks and even better memories with family and friends!