I am a big MAB fan, but JMM for sure, in terms of career. His string of fights after Chris John is pretty spectacular and epic, if you don't include getting schooled by Floy. Epic saga with Pac, where he got a draw and some losses a lot of people thought he won, and ended up witht he brutal KO victory. He even beat MAB in a severely underrated fight. Plus the wins over Katsidis, Casamayor, Diaz x 2, Alvarado were true top tier performances. The uppercut combo that ended Diaz is one of the GOAT combos in combat sports.
Tho JMM has the better career, I like MAB more tho. I think if they had a street fight, MAB would beat the shit out of JMM. He is the type of person that knows to target his oppnents ball sack, and/or would bite their jugular out of their neck. He is not someone to fuck with, and doesnt need to drink pee pee (steroids). JMM didn't get caught tho, so I won't fault his career.