Marvel\'s heroes are flawed, they have powers but because of it they have to give something up. Spiderman has no personal life, Hulk is like twenty different people and so on. And the Xmen are all basically social outcasts.
While DC\'s guys, Supes all powerful, nice family, good job, Bat\'s and Green Arrow are filthy rich and so on. Granted Bat\'s has a flaw or two with his parents dying and his back being broken by Bane.
Also Marvel are more conservitive with their characters powers while DC guys are almost godlike in many ways, Supes is well... SUPER, Bat\'s the smartest guy in the world and could outsmart god himself and so forth.
While DC has some good stuff they\'re far from perfect.