Number 5 - Argo
I prefer to think about the Kevin Smith version of Affleck, especially Chasing Amy, and as well as his role in Good Will Hunting. As a director, The Town was great. I listed it at number 6. So he's gone up one spot, something I'm sure he'll be proud to learn.
People (not people I actually talk to, but just people) are still surprised that Affleck is so successful as a director. It's that Bennifer phase that they remember.
From a history point of view, I loved Argo and learning about this. Since it was just declassified a few years back, it's probably the first that a lot of people learned about it. Argo is a good enough movie that it will likely serve as the primary source to tell the story, much like Glory tells about the 54th Massachusetts. That means inaccuracies and all for both stories will continue.
I'm looking forward to Affleck's next movie making it up to number 4.