You can say this is the fault of DC and the historical roots of most of its characters, some of whom have been better modernized. When Marvel started publishing in the early 60's, their mandate was to put superheroes and their settings in a more realistic enviroment and light. Proving after some years to be more successful in this approach, DC would start doing the same, after experiments like the O'Neil/Adams Green Lantern/Green Arrow series, but much of the roots of characters remained in fanciful territory. Batman, a great character, fought crime in a darkly fictional version of New York(Gotham); Superman does it in a brighter version( Metropolis) - other characters were in fictionalized settings like Central City, Keystone City, Coast City, Hub City etc. There is a tactile feeling to Spider-Man swinging through Manhatten or Dr. Strange being based in Grenwich Village, a feeling of familiarity that brings us closer.
By the 80's, DC was creating characters and putting them in real locations like NY and LA, but they are second tier for the most part to the main ones. Then there is the problem of context for some of the most powerful heroes. Kingdom Come Flash was an example of debate: with this godlike power, why does he content himself with patrolling one city? Or why does Superman stay in Metropolis and concern himself with petty criminals, when he should be dealing with cosmic menaces consistently, like the Silver Surfer at Marvel? Why bother with the secret identity( the glasses?please) and day job of reporter? Defenders will point to his humble, All-American raising on a farm with old fashioned values, as to why he wants to live normally. More intriging ideas were raised by Frank Miller in DK2, showing a Superman deciding he might just take over and run humanity for a change. As Thor eventually did in Marvel - Thor dabbled with the secret identity from time to time, before deciding it wasn't neccessary. And Wonder Woman always had a little less cred from me due to her garish, cheesecake outfit - it's beneath an Amazon warrior princess to wear that. The upcoming movie promises to "update" her look; the Stan Lee Creates DC series, whatever its flaws, had a more real outfit for WW - once again, the Marvel approach.
So that's just my view. DC has some great artists and writers, and you could say they often surpass Marvel in quality, but its the more real feeling of the Marvel Universe that attracts me. Sometimes the question is not who has the better comics, but the better enviroment.
P.S. On a personal note, DC has always ignored Canada. While Canada is a major part of Marvel Universe.