I'll go with Roberto if he trained his best and was in prime condition going into the fight.
At the lightweight division I doubt Manny would have lasted the whole fight, but would have put up a good fight till Duran finally put him down for good.
At the welterweight division, the fight would depend on Pacquiao's movement staying way from Duran getting close enough to hurt him while Manny moved in and out of Roberto's range peppering Duran with punches.
That would work for most of the fight but I feel Pacquiao would still absorb the type of punishment to allow Duran to get inside Manny's defenses in the later rounds and put him down.
But both weight-class fights depend on Roberto making sure he's in the best shape possible or I'll give the fight to Manny who always was at his best going into a fight
and was great enough to exploit Duran's stamina s and fighting ability when he didn't enter the ring at his best.