Civil War, for all of its flaws, has strong artwork, an understandable conflict that resonates with people about the general function of government, and lends itself to big set pieces. Plus, it has at least one crucial twist in Spidey's reveal and change of heart.
Flashpoint's a little harder to explain, but at our core, I think we'd all go back and fix something if we could, and sheer reality bending is exciting on a mainstream scale.
