The Avengers were long known as Marvel's mightiest team, but saying they were the most popular was a road too far. There are actually very few points in Marvel's pre-MCU history where the Avengers were the most popular team, as the Fantastic Four and the X-Men ruled the Silver Age and the Modern Age respectively. However, the advent of the MCU made the Avengers the most popular team of superheroes in the world, with fans learning to love Earth's Mightiest Heroes.
Source：https://www.cbr.com/best-avengers-comics-for-non-avengers-fans/
