I don't have a favorite manga/anime, since all those who are weekly updated are subject to change in my taste.
As for complete ones, though, for Anime it would be both Code Geass and Death Note for the intense scenario and the type of the protagonist (it's called "chaotic", non-evil, non-good), and for manga I'd go for I"S as romance and Shaman King as shounen. I hold an exceptional pleasure for Yakitake!! Japan and Great Teacher Onizuka, though.
Sidenote: I don't like Pokemon as a manga/anime, I just don't feel like it. Don't pinpoint attack me.