On actual Knockout-Cold power it would be close for me between Pac and Valero, although as Snakey suggested Valero hasn't knocked anyone out at top level yet. Also, a funny sign for Valero was that, if you never saw it, he literally battered DeMarco into submission, some of the shots he caught him with would have no doubt in my mind starched any of his previous opponents no sweat. Maybe now he's stepped it up he will struggle to knock anyone out. No ideas as to the quality of DeMarco's chin though. Maybe I do lean a little towards Pac.