Arguello is number 1. That's not debatable. Nelson ain't NEAR Argeullo's league as a puncher. 2nd is arguable, but I think I'd actually go with Corrales. With the exception of Arguello, I don't think there was any other puncher in 130's history as devastating as Chico.
Nelson was a much better puncher at 126 At 130 his ko record wasn't that great Arguello is #1 in my book Corrales was up there. Boza had very good power at that weight.
Alexis Arguello was probably the hardest puncher that the division ever saw. A really young Oscar Dela Hoya. Edwin Valero. Manny Pacquiao. Diego Corrales. Acelino Freitas. A really young Floyd Mayweather.
Not only did Arguello hit hard...but his delivery technique busted people up. Take a look at Alfredo Escalera's face after both of the Arquello fights. And Alfredo Escalera was a very good fighter in his own right...and could have dominated that Division if Arguello hadn't been at the top.