It's really hard to choose because there are so much good characters in both comics. But because i like the flash and batman, I would say DC. In terms of power it is Marvel for me though... LoL
I know a lot of people prefer marvel because there characters are more relatable. I agree with this, but at the same time that's why I prefer DC. The characters feel like actual superheros, not relatable humans. I grew up with DC also so I'm biased (:
DC, hands down for me.
I`m a huge fan of the batman comics and movies, and I love all the cartoon adaptations that came out too. (Teen Titans and Young Justice, anyone?)