(6) Pythagoras vs. (2) Plato
Someone's getting his chiton ripped up in this matchup. These two ancient Greek heavyweights both have a lot going for them. Both made their marks on philosophy, and both were known as strong mathematical thinkers. (It's sometimes forgotten that Plato was an early mathematician who helped stratify the discipline into applied math and pure mathematics.) Plato had a number of notable students, including Aristotle, while Pythagoras had a whole brotherhood following his teachings. In fact, Pythagoras' ideas about rational philosophy set the stage for and influenced a lot of Plato's work. Which Greek is the bigger genius, though?
[See the whole bracket here.]