I think we just got a very important hint from Oda.
Akainu - Absolute Justice
Aokiji - Lazy Justice
Kizaru - Unclear Justice
Fujitora - Blind Justice
Ryukogyu - ... (Street Justice?)
Coby - Honest justice
Also I think we just got another hint. If you connect the parallells and look into what Aokiji said about Garp having a knack of raising enemies we might finally get a clue as to who Dragon really is - a former protege of Garp. Perhaps his real son or, as we have seen in One Piece before, a ”son" without blood connection.
Garp = Jiraiya
- Older men with white hair
- Jovial types outwards but secretly serious underneath
- True legends and part of trios consisting of two males and one woman
- Trained three (?) young men that would go on to become some of the strongest in the world (Nagato, Minato, Naruto - Dragon, Kuzan, Koby)
If this is true then Nagato/Dragon had unrivalled potential but both saw injustice and strayed from the path. Minato sacrificed himself for the greater good, as will Kuzan. And the true hero and heir is the third one, Naruto and Koby.