Vince Lombardi's Packers team made the Championship/Super Bowl in 6 of these 8 years, winning 5 times in 7 years and losing once. In their 5 victories their average margin of victory was 20.2 points.  Their loss in 1960 was by a mere 4 points. Their victories in Super Bowls I and II were by an average of 22 points led by QB Bart Starr, RB Jim Taylor & LB Ray Nitschke.

QB Otto Graham led legendary Coach Paul Brown's teams to 6 straight Championship games winning 3 of them. The wins were by an average of 24 points and the losses by a slim 6 points, both at the hands of the early 50's juggernaut Lions who also made this list. Graham is one of the best quarterbacks of all-time and Brown one of the most innovative coaches. 

HOF players Montana, Young and Rice won 3 Super Bowls in 7 years under Walsh/Seifert. They rank this high because in 3 other years they lost the NFC Championship to the powerful & eventual Super Bowl Champ Giants & Cowboys whose '92 and '93 team is some consider the best team of all-time. This period occurred when the NFC won 13 straight Super Bowls and NFC Championship became considered the Super Bowl.  Two of their Super Bowls were won by 45 and 23 points. 

This Steelers, built around solid drafting & Steel Curtain defense, won 4 of 6 Super Bowls. They had to battle the powerful Dolphins & Raiders in the AFC who had won 4 Super Bowls in the period, and then beat Dallas in 2 Super Bowls, a team many consider the best Super Bowl losing team of all-time. Their best team in '76 lost in the playoffs when RB's Harris & Bleier were injured in this rushing oriented era or they probably win 5 of 6.

This Cowboys team was loaded with talent via the NFL Draft & a massive trade haul for RB Herschel Walker. They won 3 Super Bowls in 4 years by 21 points per game. They did so while fending off 3 NFC HOF coached rivals for the ages, the Giants, Redskins & 49ers, who joined the Cowboys as the best conference in NFL history. The 4 teams won 11 Super Bowls in 12 years (1984-95), albeit the Giants & Redskins wained in the 1992-95 period.

Quarterback Bobby Lane led Coach Buddy Parker's Lions to 3 NFL Championships in 6 years while losing one in that period. They, in part, appear high at first glance, but are so because they beat the 50's dominant Browns (also on this list) twice during this period & also lost to them once.    

The Patriots ruled the NFL for most of 2001 through 2018 winning 6 Super Bowls and losing 3 in those 18 years. Some consider that the dynasty period but there was not sustained dominance to be considered a dynasty as they didn't win the Super Bowl for 9 years in the middle of the period. However, the pinnacle period, 2014 to 2018 when they won 3 and lost 1 in 5 years was. They might have ranked higher but they eked out each win. 

Based on "dynasty" defined as "sustained success" the Giants put in the 2nd best "lengthy dynasty" in NFL history (2000's Patriots). They played in 5 of 7 championships from 1933-1939, 6 of 9 (1933-41) and 8 of 14 ('33-'46). Unfortunately they only won two of these games or 2-6. They would have ranked higher on the list with more championship wins.