For "Greatness" it's hard to go past 11 years and 25 fights undefeated at FW and NINE defenses of the World Title.
Head to head matters of course, but experienced fans know that "styles make fights" and "anything can happen on the night", which is why longevity as champion is the most significant factor. 10 wins over Top 5 guys > 4 wins over Top 5 guys. Sample size matters.