I Like both, but I like the manga just a little bit more
There are sometimes (wich seems like is always)where the manga is MUCH better than the anime (Bleach, Naruto, Shaman King, younameit)it leaves to your imagination how the chars voices sound like and it will always be the canon story, but the in the anime you have much more production behind it, music, animation, voice actors and merchadising (figures, posters, music Cd´s) wich makes it more entertaining.
Personally I think that the person who just sees the anime without reading the manga (before or after watching the anime) its just lazy.
Pax