There's almost nothing more difficult or more controversial than comparing one era to another. No matter what sport—baseball, basketball, hockey, golf, boxing—you'll have some fans that say "the best" from 1960 was 100 times better than "the best" from 2012.
Who can say for certain whether or not Sandy Koufax was better than Greg Maddux. Or if Shaquille O'Neal was better than Wilt Chamberlain. Or if Tiger Woods was better than Jack Nicklaus.
But that's half the fun of sports: We cherish the games' histories and use them as a measuring stick for greatness.
So, too, does this list.
Sure, if there was a way to transport the 1966 Packers to the present day, they'd probably be thumped by the very worst team in the NFL. Heck, given the improvements in speed, size and strength, who knows if Jimmy Johnson's Cowboys dynasty would even have a shot against a bottom feeder of today's NFL.
So instead of trying to determine whether or not one team could time-travel and defeat (or lose to) another, I offer another criteria: dominance.
Which teams were the most dominant of the particular season in which they played?
NOTE: To avoid redundancy, there's a rule here for which teams qualify. Five years must pass before a team is allowed a "repeat" entry on this list. So, while the 2007 Giants and the 2011 Giants won Super Bowls, only one is eligible for this list.