I'm going to go out on a limb and say Arguello simply because his competition was superior. But you can't go wrong with the two because once they got an opponent hurt about 95% of the time the fight would be stopped soon after. Two of the greatest finishers in the history of boxing, and their style,skillset, speed,and power were very similar to each other pound per pound. Both fighters were aesthetically pleasing to watch.
Louis - he often did it quicker. Alexis was more patient and (usually) slowly applied his superiority before delivering the coup de grace.
