DC and Marvel are different, so it is hard to choose one over the other.
But I do tend to veer towards DC. Simply because they have the most iconic characters and cities; Batman / Gotham, Superman / Metropolis.
Both are very distinctive in feel, look and as well the resident hero and villain population. That sticks and requires more creativity. Marvel has no such thing because it has developed over the time to be more "realistic".
I also like that Superman is a childhood dream, with the glory that comes with being a traditional revered hero and the bright future. Not to mention awesome powers and a good life. We might want to be him, but at the same time he is not quite what we are, flawed humans.
Batman is the opposite; Gotham is a dark, depressing city and Batman will never be able to have a normal life and future. He is the broody, tormented hero, who despite his cynism and lack of superpowers, keeps fighting. We don't want to be him, but he is closer to us than Superman in a way. Also, Batman and pretty much all of his bat family are basic humans, with no powers. Yet he is a prominent hero. Marvel never created a powerless hero, who is the flagship, as well known if not more known than their famous characters.
I think both characters and Gotham and Metropolis are something that just stays with you for much longer, than the long roster of mostly mutant heroes of Marvel who usually live in standard cities like L.A. and N.Y. That does not mean Marvel is bad though.