The Broncos and 49ers had great defenses in the 2012 regular season, even if it wasn't readily apparent in the playoffs.

Seattle's "Legion of Boom" came into their own as a vile force of nature.

Chicago's havoc-wreaking led to a seemingly endless loop of defenders scoring touchdowns.

Pittsburgh's aging defense gave up the least amount of yards in the entire league.

But which NFL defense, heading into 2013, is the best?

Considering what each defense accomplished in 2012, and assessing what their 2013 moves mean to their squads as a whole, this is a subjective look at which defensive unit looks strongest going into a new season.

And besides, it makes for some good arguments, doesn't it?