Ben's standup is average at best. He has good and powerful kicks but he rarely throws them with good combos.
Aldo is significantly faster and throws much better combos while possessing superior head movement. Edgar can move in and out without much fear of guys like Maynard (even though Maynard beat him down for two rounds) and Henderson, but Aldo has the speed to catch Edgar with many points of attack.
Ben's kicks may be more devastating power wise, but Aldo's come amidst combos and quicker than Ben's do.
I believe Edgar has one way of winning this fight and that is via decision, which is highly unlikely even if Aldo gasses. If Aldo doesn't finish him in the first two rounds, I think Aldo's gas tank will still be good enough to last him into the third and fourth rounds. Edgar will have to steal some of the early rounds and I just don't see that happening.
I think Aldo tko's him inside of two rounds.