I think Pac hits more explosively, and thus, has more of an effect. The speed really does help augment his natural power, though Ortiz is fairly quick as well. I can't seem to pick between them.
I think Ortiz if you measure power, but it really doesn't matter if he cannot land it. Berto might punch as hard as Manny, but it doesn't mean much. Manny isn't just this fast guy who outboxes guys, he busts them up. He is a sharp puncher who can punch pretty good. I would say his punching power is a 7 while Ortiz might be a strong 7 or an 8. But Manny is so sharp that there is no comparison.
Pac didn't put ALL of his opponents on the canvass the way Ortiz did before he ran into Floyd's straight right hand.
If they were to have a go on one of those punch machines you see in an arcade then I'd back Ortiz if I were to bet on someone.