Well, I mean the strongest/hardest punch p4p speaking. not the best puncher (wich I believe is Pavliks case) , the strongest.That's hard to answer because there are different kinds of power punchers. Miguel Cotto is by far the best what I like to call, "wear down" punchers in the sport but then you got guys like Kermit Cintron who, when they land, opponents will fall. Samuel Peter doesn't land right most of the timeso I wouldn't vote for him. Then you got guys like Pac-Man who combine speed with power to give the illusion they are devastating when they are really flashy power punchers and not so much devastating punchers. Klitsko doesn't rely on his punching power for the most part so I wouldn't call him a pure power puncher, and the list goes on.
All in all, I'd say it's a toss up between the likes between Kelly Pavlik, Kermit Cintron and Miranda who is all about power.
My vote: Kermit Cintron because he's the true "Either get KO'd or KO" fighter. He's the true KO man.
I'd put Randall "The Knock out King" Bailey up there as well. He's obviously the most powerfull puncher at 140lbs along side Ricardo Torres. A fight between those two could be explosive.
May I ask, what is Edwin Valero not doing up there as well? LOL