Enigma points out a very good point about these superheros, and I really wanted to dwell on it. The one thing that makes Marvel in my opinion better than DC characters is the stories behind the secret identities of these heros. Other than Batman, every superhero in DC is practically flawless, meaning they barely have any human element to their personalities. A large part of that is because for most of them, their superhero side IS their true identity, and they have these "secret identities" in order to blend in to society. Superman was BORN Super, Wonder Woman was born as the warrior amazon princess, Aquaman was from the city of atlantis, etc. Batman is the only one that has an actual human element.
Marvel on the other hand, I like to look at it as a world with a bunch of batmans ahahah. Many Marvel characters for the most part weren't born with their abilities, or didn't know they had the abilities they have until it was awaken some how. I think there is more to say for characters who struggle to coup with the fact that their lives will never be what they once were. Dr. David Banner (Enigma says Bruce, I say David, but its the same person) wasn't born as the Hulk, and he hates the fact that this beast is stuck in his body. Peter Parker is just a teenager and is doomed to deal with the responsibilities of his powers while continuing to try to juggle a life as a teenager. The institution for Gifted Youngsters (Home of the X-men) is a building full of people (mostly children) who need to be sheltered in order to be protected from a world that hates them simply for who they are. I think there's far more to love in the Marvel world, and to me it personally starts with a characters true identity before the Super Hero.
Just bouncing off what Enigma was saying