What source states Boba became better than Jango in H2H?
And I think it'd be a close fight, worth debating, but there is an evident disparity in physical capabilities that I don't see either Fett overcoming. Maul's battle precognition, noticeably superior combat speed, far superior strength and comparable skill should be enough for him to win.
@Ant
Nope. EU's Force users should be far superior to non-Force users because oh their Force Augmentation.
But in the movies and TCW they are not. Obi-Wan struggled against Jango, Maul struggled against Vizsla. There are more examples, especially in TCW.
But yeah, as a NewGuy said, according to some EU materials, there is a room for debate. A huge room possibly.