If we're comparing, like, anime vs. manga versions of the same series, it really depends on... well, if the anime adaptation is good. (Obviously. lol) Well, it's really hard for me to make a generalization about something like this. The world of anime/manga is too broad... There are good anime adaptations, just as there are bad ones. It mostly depends on what I'm in the mood for, honestly, but if I had to pick one...
Personally, I'd have to go with anime, I guess. I like watching the characters moving around and such... it makes them really come to life, and some subtle movements/motions/effects just can't be properly depicted with still images. It better portrays characters' interactions with each other, and therefore their relationships with each other. (Though, there is enjoyment in reading the comics and imagining the scenes playing out in your head, as with reading books that are strictly text. Manga, which is kind of in the middle of that spectrum, is kind of odd, though. I'd prefer either extreme, depending on what I'm in the mood for.)
And having sounds/music is really a plus for me. I'm a sucker for anime/shows/movies that have great soundtracks. (Music appreciator over here.)
Anime is a more versatile medium and has greater potential than manga because of the animation and the sounds. Manga has a very classic feel to it, and sometimes anime adaptations don't do the original justice (by following the manga's plot-line inaccurately/changing things, adding fillers, etc.) but overall, as a medium, my vote has to go to anime. I don't mind things like fillers that much. They're often enjoyable.
On a side note, while anime has so much potential, it's sad to see how people can sometimes corrupt it because of the high demand for viewers and money. I think excessive fan-service and things like that really detract from the plot-line. If I wanted to see half-naked chicks, I'd look for them elsewhere, not while I'm trying to enjoy the show and what's happening in the story. Also, many times, the voice actors have really irritating voices for the sake of "cuteness". The over-sexualization in anime is really overdone. Like, random cleavage shots really contribute nothing to the plot. I guess it's the same issue as with my preference of books or anime/tv shows vs. manga/comics - I prefer either extreme of the spectrum rather than something in-between. Eh, despite all of this, anime has my vote.
(I accidentally wrote a novel. Oops.)
