It has been argued to death by many fans as to which era of Power Rangers should be considered the "Golden Age." The two eras that fans argue about are the "Zordon Era" and the "Saban/Judd Lynn Era."
The Zordon Era fans who claim that this era was the Golden Age have many reasons to believe so. The Zordon era consisted of MMPR seasons 1, 2, and 3, Zeo, Turbo, and In Space. And for some fans, Lost Galaxy. For starters, fans go on about how this era was when Power Rangers was truly at it's most popular. No doubt about that. Both MMPR and In Space were huge. Lost Galaxy was also quite popular, being the highest rated Power Rangers season in terms of TV ratings to date. Fans also mention that this era consisted of the longest story in Power Rangers to date (six seasons long. Sometimes seven) which all came to an end with a bang! Fans believed that this era was when Power Rangers was at it's most original and truly described what a Power Ranger truly was. Fans loved how everything in these seasons were strongly connected into a whole single universe.
What Saban/Judd Lynn fans did not like about this era was it's "inferior" quality compared to the era that would succeed it. And also not liking how this era shows off by being the symbol of the Power Rangers franchise. Fans of this era also didn't like the Zordon Era due to how the story started with a completely different cast than how it ended. Plus, they didn't like how this era wasn't faithful to their Sentai counterparts as much as the Saban/Judd Lynn era was.
The Saban/Judd Lynn era consisted of Lost Galaxy, Lightspeed Rescue, and Time Force. Some fans include In Space due to it also being written by Judd Lynn, thus having the same quality as the other shows in this era. Plus, fans don't mind it's connection to previous seasons, as it was vague, similar to Lost Galaxy. Lots of fans love to include Wild Force in this era as well. The main reasons are because Wild Force, despite being a Disney season, and not being written by Judd Lynn, was still created by MMPR Productions before the crew moved to New Zealand. Thus, having a similar aura to it like it's previous seasons. Plus, Wild Force had a team up with Time Force and had the Forever Red episode to wrap the era up. Whereas Ninja Storm cut it's ties from it's previous seasons. Other fans also include RPM as part of this era (despite airing many years later), due to it being written by Judd Lynn, and having the same quality.
Fans of this era love to claim this era as the Golden Age, mostly due to it being when Power Rangers was made at it's best. Other fans love this era due to how loyal they were to their Sentai counterparts. Of course, this depends on each fans' tastes.
Overall, the fandoms of these two eras are still very much at each other's throats. However, there is a third fandom out there that basically likes the entire Saban era. And is just as big as the other two. So how can these two fandoms calm down? Well, the major elements that play a role in this are quality, nostalgia, originality, and stuff like that. Major differences here. In fact, Sentai also plays a role in this. As Sentai is much closer to the Saban/Judd Lynn era than the Zordon Era. But the weird thing, many Zordon fans also like their Sentai counterparts from Zyuranger to Megaranger.