I tentatively pick Chitalada. He used to cut down from 130, and when he did it right he was a fucking animal. I don't think his jab is better than Oba's, but I do find it smoother. Last fight I watched of Oba was the Susumu Hanagata rematch - Oba lost the first when he was a kid - and he had massive trouble with Hanagata's legs. A quick footed mover who's could get a quick read of Oba, made his jab fall short and forced Oba to lead. As I recall, Oba looked pretty lost when he wasn't in control, centre ring. I feel like Chitalada, with his size advantage, ATG jab and fleet footed Ali-esque legs, wins a close decision. Beautiful jabbing contest though.
Your post was good enough to sway my opinion, because my initial instinct was to pick Ohba. But yes, two of the three best jabs ever at flyweight in this matchup, with the other great jabber being Kingpetch.
I'd say Canto was definitely better than Kingpetch. Harada too, IMO. Those two would actually be my picks for two best. Been awhile since I watched Midget Wolgast, but I seem to recall him having a damn good jab as well.