Manga usually gets the more outlandish plots. With a manga, you could get anything from top tier quality to the worst cancer ever drawn and published. With anime, the range is less wide; you're either getting a good manga with added sound, colour, &c or you're getting a not so good manga with added sound, colour, &c.
Honestly, I'd usually at least read the manga to get the full story, no cuts. Anime adaptations are usually watchable, but few are really good.
Added sound and color would make a visual novel. Motion is the biggest advantage anime has over manga.
I prefer manga because the art is more attractive and I can follow the story at my own pace. Anime is usually adapted from manga and they change so many things it doesn't resemble the original; I also dislike the voice acting, be it in japanese or english.