As a GM, the factor you need to balance the most isn't power level, it's time in the spotlight. Every PC should matter. Every PC should have a chance to shine.
The Fate Ladder is the GM's best friend. When deciding your campaign's tone and feel, you get to decide just what "Average" means for a superhero. Can an "Average" attack roll knock down a half-dozen armed thugs in an alleyway? Or is it just enough to give a single mugger a bloody nose on a novice vigilante's first night out?
The ladder should be used with a character's power facts in mind. A Legendary feat of strength for the crime-fighting phantom Covenant might be Fair for Mack Atlas, the world's strongest man.