Manga and anime, like paw said, are so much more diverse than American comics today. Loved the superhero books when I was younger, but growing up I left them by the wayside and American comics ace me very little as an adult to keep me interested. There are gems like anything BKV puts out, some Garth Ennis stuff, some indie books...
But manga/anime have something for everyone. I got married back in September, and my wife, whose only experience with anime was Avatar (more anime-ish than anime), is already hooked on shows I was watching. Now we watch Space Brothers, Sword Art Online, and Fullmetal Alchemist Brotherhood together. We just watched Summer Wars last night.
The only comic I have been able to get her to read currently is Saga. She also reads Buffy.
More to the point of the thread, DBZ was awesome when I was younger. But, like the superhero books, I left it behind. Anime gave me things to keep me interested as a teen, then as an adult. Comics didn't do that as much.