For movies using real actors I would definetly pick subtitles, as the actors take into account the pace, the intention etc in their work as professionnals and I don't think someone dubbing can completely grasp them. Even if they do, they might not be able to completely mirror these intentions.
However, even in their original languages, animes are dubbed. So my preferance between sub and dub really depends on quality. And for Ghibli movies both are very good.
I like dubs better just cuz it is hard for me to read the subtitles and watch the film at the same time. Saying that, sometimes when I really get into a subbed anime, It's like i'm not even reading the subtitles and the characters are speaking in English? Does anyone else get that!?