It was a hard choice between 2 and 4, and now I see that most people choose either of those two. However, I picked 2 because of the variety in the panels. All of them are great...I guess I'll have to buy it to see all the pages in color. Keep it up!
While agree that each one brings something to the table, I think number 2 brings the most variety and complexity. For starters there is lots of interaction with the two characters, with excellent poses depicting high intense high speed action. Out of the four this one displays the greatest level of diversity in skill sets as well. This image presents a well balanced sample of both environmental and character work.