"What's the best way to set New Yorkers to bickering? Ask where to find the best slice of pizza in the city. No subject starts a battle faster—not bagels or hot dogs or chopped liver, not even the primacy of the Rangers or the fastest route to J.F.K. Pizza, introduced to New York in 1905 by Gennaro Lombardi, who saw it as a way to use up the day-old bread in his Spring Street grocery store, has lo