Arthur Abraham by a mile Mayweather is the harder puncher at 130 (career wise), when both turned pro at 130 Mayweather hit harder. Mayweather moved up & tended to use less power and depend on excellent matchmaking, natural speed & high ring IQ Broner had to slug it out more often as he moved up, because he was not as gifted as Mayweather :smoke
Mayweather had the power, even at 152, to keep a LHW Canelo off him. He might not have one-punch KO power, but he hits harder even later in his career. To compare Broner in his best win - a faded Paulie - and the quality chinned opponents Mayweather came up against isn't much of a fair comparison. Broner - 23 KOs after 35 fights. Mayweather - 24 KOs after 35 fights.