I have liked both, sometimes on the same series, but often I will prefer one or the other, and of course within the anime you have a sub or dub preference. Manga is often a better bet over the long term, with very little filler, whereas it's almost a necessity in anime, to keep a decent distance behind the events of the manga. In a way, that's the only drawback, anime is more readily accesible and better looking than manga, but the filler can often be diabolically bad, as opposed to the manga, which can be very stylish and consistently delivers on plot and character development...