Will have to see what Morales look's like after the longest layoff (rest) in his Boxing life first...
Morales of course. Barrera was able to go full 12 rounds against the current P4P #1(Pacquiao) fighter and also 12 rounds in a close fight(many thought he won, myself included) against the current P4P #3(Marquez). Morales lost to Pacquiao in the third fight in brutal one-sided fashion then struggled against journeyman quality David Diaz, he's far more finished it isn't even close in my opinion.
Morales is more shot. recently he's been blown-out by Pac, lost a wide decision to Raheem and lost to an average fighter in David Diaz. Barrera on the other hand gave Marquez as good fight and at least survived 12 rounds against Pac. If you jsut compare there recent performances it's pretty clear.