I think Arguello wins a decision or stops him late in a back and forth battle. They're similar in a way but Alexis holds more aces what with his height, leverage and spacing. He also had quicker punch release. Marquez is just too easy to hit clean for him to overcome Arguello, who's a better, longer version of Marquez. I'll give Juan Manuel the benefit of doubt and say he makes it to the final bell, because he has one of the biggest hearts in the history of boxing.
JMM can't withstand Arguello's best shots at this weight. He gets stopped late in a very competitive, action-packed fight.
I just see that right hand landing again and again on Marquez, landing more frequently as the fight progresses. Late TKO for the Thin man.