Not to just talk about comic book superheroes, the Primarchs (and many other WH40k characters) are pretty inconsistent.
They have many feats that make them as if City level was their maximum, such as seeing impressive city-scale earthquakes, barely surviving nukes, having a hard time lifting the weight of a Titan, but then have them fighting demons that destroy planets, being much stronger than Psychics that reality warping planets, Magnus is superior to Malcador who was able to hide a planetoid with his Psychic powers, in addition to there being a couple of quite controversial Solar System feats such as Sanguinius protecting himself with his wings of the flames of the birth of the Red Angel, those flames covered the solar system and affected the stars causing a nova, or the daemon that created a fortress the size of a solar system and sustained with its power since when Sanguinius killed him the fortress began to collapse, or the fact that Horus damaged the Emperor who has supernova level attacks and fought with beings that eat stars (the Void Dragon) although Horus was repowered by the chaos gods, he was worried about Sanguinius and in the next book we will see the fight between boths.
So you can easily see people discussing whether the Primarchs are City level, Planet level or Solar System level.
They have many feats that make them as if City level was their maximum, such as seeing impressive city-scale earthquakes, barely surviving nukes, having a hard time lifting the weight of a Titan, but then have them fighting demons that destroy planets, being much stronger than Psychics that reality warping planets, Magnus is superior to Malcador who was able to hide a planetoid with his Psychic powers, in addition to there being a couple of quite controversial Solar System feats such as Sanguinius protecting himself with his wings of the flames of the birth of the Red Angel, those flames covered the solar system and affected the stars causing a nova, or the daemon that created a fortress the size of a solar system and sustained with its power since when Sanguinius killed him the fortress began to collapse, or the fact that Horus damaged the Emperor who has supernova level attacks and fought with beings that eat stars (the Void Dragon) although Horus was repowered by the chaos gods, he was worried about Sanguinius and in the next book we will see the fight between boths.
So you can easily see people discussing whether the Primarchs are City level, Planet level or Solar System level.