Marvels C.H.A.R.A.C.T.E.R.S are more grounded in reality IMO they have personalitys and they are not one trick gimmick characters like Flash (we get it he can run fast)
The main difference between Marvel characters and DC characters lies in their stage of development. DC characters were created during the 1940s and therefore are very much tied to World War II history...this largely accounts for the multiple Earths and legacy characters. The need to explain both their history and the multiple comic companies they have bought out over the years. This also accounts somewhat for the powers.
The DC heroes are somewhat viewed as godlike because most of them were created when comics had no sense of continuity. The powers, therefore, tend to be more iconic. You have a king of the seas, and incredibly fast runner, a godlike father figure, a human athlete, etc. etc.
Because they created these archatypes, people tend to assume they are more powerful or less human than Marvels. Flash
is comic's speedster. Aquaman
is comic's king of the seas. And Superman
is the end all be all of a superhero. However this has merely to do with their prominence, not their actual ability. Originally DC characters were not that powerful, and probably far more grounded in reality than Marvel characters were when they first appeared.
For example, Superman originally was from a planet who had a higher gravitational pull. As a result he could "leap tall buildings" (not fly) and lift heavier objects. Not a huge stretch by the laws of physics. Later he would become an uber powerful near cosmic...who may one day evolve to Godhood. However that was not the original intention of the character. This is similar in relation to Flash, Hawkman, and Aquaman who started out with far more down to Earth powers. Even Batman started out as a reasonably decent fighter with a great physique who carried a gun to fight crime...a little more believable than a guy with 15 graduate degrees and 127 black belts.
why do you think Batman is DC greatest asset?
That's just fanboyism.
because people can relate to him far more then superman or Aquaman characters who havent changed much since there conception.
Well we just covered why that isn't the case with Superman.
As for Aquaman, ask any Aquaman fan (do they still make those

) and he/she will tell you: he is one of the most inconsistent characters in the DCU. He's gone from a relatively fast swimmer who can talk to fish, to an underwater Superman, to a magic based character and now an undersea Conan.
Marvel characters also have far more interesting powers Characters like rouge are a masterstroke in design she can absorb the powers of others but prolonged contact can kill the victim this creaes the situation where she can never really get close to people she isnt a god like amazon with no real weaknesess like WW.
Understand, while the mainstays of DC are pretty basic, due to their age (and their powers play out a little more complexly...but they are somewhat basic for sake of argument), DCU B and C listers are just as unique. For example characters like Obsidian (who lives in shadows), Dr. Fate, the Spectre, Deadman, Beast Boy, The Doom Patrol, Teen Titans, etc. have all given us characters with unique abilities.
And also remember, part of the reason characters like the Flash and Wonder Woman don't seem so "unique" or "interesting" as Rogue or Cyclops (in terms of power) is because their powers have gotten played out so many times since they were created. At one time a speedster was a relatively unique idea.
new marvel characters like Darwin whos body evolves to combat each situation (underwater he grows gills,if he has absolutely no chance of victory in a battle his body simply teleports him elsewhere) and the late Maggot (no stomach instead two giant slugs who eat matter and burrow back into the stomach cavity to release the food into his body) are also great far better then DC IMO.
Maggot, ugh no. A man's who has the power to shut down a restaraunt...no thanks.