According /Film’s Angie Han, Marvel trounces the competition for two reasons:
They are better at storyline continuity:
While all of Marvel’s movies are connected, by virtue of belonging to the same universe and timeline, they’re not all intertwined. It’s quite possible to enjoy Guardians of the Galaxy without ever having seen The Avengers. Heck, you can understand Captain America: The Winter Soldier without ever watching another movie starring Captain America. But the reason Marvel feels like a cohesive continuity is because the individual installments do line up for anyone who cares to look. It’s not that every detail has to be perfectly consistent. We’re okay with certain actors having dual roles, for example, and we don’t bat an eye at the nonsense spewed by Marvel’s many scientist characters. But Marvel is pretty good about sticking to its own internal logic.
They are better at “practicing patience:”
Because Marvel tries (and usually succeeds) at delivering complete individual movies, it can take them a while to build up to major overarching storylines. Iron Man may have set up the rest of the Marvel Cinematic Universe, but it still took us another four years and another five films to get to The Avengers. Captain America lost Bucky in The First Avenger and learned of his fate in The Winter Soldier, but didn’t truly get to reunite with him until Civil War. And Captain America and Iron Man’s personalities first clash in The Avengers, but their friendship continues developing through Avengers: Age of Ultron until their differences come to a head in Civil War. While Marvel famously maps out their storylines years in advance, they treat patience as a virtue and their films are better for it. Not only does their slow-burn approach give individual films room to breathe, they ensure that the payoffs, then they finally come, actually feel earned.
In her piece, Han contrasts Marvel’s success with the relative failures of both the DC Cinematic Universe (helming the current awful Batman/Superman series), and Fox (in charge of the latest string of X-Men movies).