Marvel, because they have the darker, more "adult" comics(I'm looking at Ghost Rider). I also find their comics more entertaining as well. Gotta love IronMan.
DC does have some of my favorite childhood heroes though, like Batman and the various Green Lanterns.
Well I would say marvel now espeacially since they have my major super hero favorites but DC is underrated besides the new justice league which is gay. Actually I'm gonna ask what you favorite super hero is in a new thread.