In a firefight and all out brawl? Pac. But Pac would have to get it done in 6 rounds. Iron-chinned dudes like Clottey, Floyd, and Mosley were frightened of trading w/ Pac and for good reason. Spence won't want that kind of smoke. Opponents have to sap Pac's energy these days by running or wrestling.
Spence doesn't take a lot of clean shots. He always ends his offense with defense and isn't there to be hit after a combination. He will keep it long and force PAC to work, then pick his spots and go to work on the inside. Pacquiao has a big edge in the mid distance where he lands sharp unorthodox shots, but I don't think he can hang with Spence on the inside or at long range. The footwork of Spence will win him this fight as he'll be able to nullify PAC's lunging attacks, then get inside when he wants.
Depends on what range the slugfest is fought at. If Spence can close the gap effectively and keep it an inside brawl, he has the edge. Pacquiao's best chance is from mid-range and to time an aggressive Spence coming in. But if Spence can take his shots and really digs in, I think he has the better stamina now and would have a decided advantage - especially given his brutal body attack.
Spence is a consistent body puncher, but I wouldn't say he's a brutal body puncher like an Inoue. I think he stopped Ocampo w/ a body shot, but I haven't seen his body shots actually visibly hurt a good opponent. Correct me if I'm wrong, though.
