With the little amount of anime I watch I don't really care, I usually prefer subs because the dubs are so annoying, but If it's a comedy anime then the original language is usually annoying as well. I can tell you that I prefer elfin lied in it's original language, and that's probably my favourite anime.

However with foreign films (which I watch a lot more often than anime) I always make sure it's subbed. The subs aren't done by fans which means they make more sense to read, and the original language has better inflection and is usually a lot more pretty. Especially on French films.