In connection with the Gusta Panino and Gusta Osteria establishments, Gusta Pizza is probably the most popular place to get a pizza with the Neapolitan flavor. The crust is a perfect combination of doughy but not too much, and the standard menu has some solid choices. Also, if you are willing to try something new, they have some fun specials--usually including some toppings that you typically won't find in Florence. It's a popular spot, so you might want to think about arriving a little earlier than the typical Italian lunch hour (before one or two) so you can get a good seat and a feel for the fun atmosphere.