Superhero comics are about inventing godlike beings to confront the world's evil for us. Therefore, I think a retelling of the origin of Batman or Captain America would work best. These comics embody the basic myth: that superheroes arise in a time of need to help us.
I give a slight preference to Cap's origin since it includes the common Marvel theme of science and technology (i.e., progress) as part of the solution. Take a brave American patriot...bolster him with our technical know-how...create a remedy for the world's problems...doesn't that represent America's view of itself today?
Therefore, I'll suggest CAPTAIN AMERICA #255 by Stern and Byrne. It combines the skilled proficiency of modern comics with the classic themes of the American mythos. Other comics may fit this description also, but this is the one that comes to mind.
Someone suggested a Superman story. To that I say no way.
In general, a Superman comic is like a Star Trek episode. From Smallville's bucolic farms to Metropolis's white towers, it's our idealized version of how the world should be. As you'll see in a typical Superman-Batman teamup, the comics themselves suggest this. Metropolis represents our bright side and Gotham City our dark side.
Which is fine, but the question asked which comic represents the actual society it came from, not the aspirations of that society. A Marvel comic is more likely to fit that bill. I've picked the origin of Captain America over Spider-Man or the Fantastic Four because, again, Cap was created to fight evil. That's American superhero comics in a nutshell.
Note: If this were 150 years ago, I'd suggest a cowboys 'n' Indians comic book. It would star a John Wayne type who defeated Indians, outlaws, and wild animals (i.e., evil) with the help of his repeating rifle, the railroad, and the telegraph. As a bonus, he could have a Bruce Wayne-style origin. Indians massacred his family when he was young, so now he wants revenge on the "dirty redskins."
For more on the subject, see Why Write About Superheroes? and America's Cultural Mindset.
Below: America's self-concept: the white, male, straight-shooting champion of justice.