Marvel did a better job of modernizing earlier than DC, imo. Iron Man spent a long time carrying around a metallic fabric suoersuit in a briefcase and carrying on an absurd secret identity life where Iron Man was his bodyguard and they were never seen together like Superman/Clark Kent. It was very Silver Agey.
But, Marvel moved past that earlier than DC did and gave more modern takes.
Marvel heroes also tend to be more down to Earth and less powerful than DC heroes, which I think makes them more relateable. DC heroes tend to be empowered by aliens or magic, while Marvel heroes are more likely to find power inside themselves, somehow (X-Men, Spider-Man, Cap, Iron Man, etc.). Batman is the obvious exception, which is why I think he's #1 for DC over guys like Supes, GL, or WW.