I admit that I prefer to watch most anime with subs. The the voices are interesting to hear, and for me tend to reflect vocally what the character is doing physically. Movement and stature are a part of culture, and this is reflected in art and animation. I feel that often, American/English voice actors sound like they're trying to hard.

Additionally, more removal of content takes place in a dub than a sub. For example, in the show Beck, a central trait of the main character is the fact that he speaks english very poorly. Because they obviously can't demonstrate that while he's speaking English, they just write that part out of the show, and it alters the storyline in certain episodes.

Of course there are exceptions to this. I like the dubbed version of Cowboy Bebop and Tenchi Muyo. And I do think American video game voice actors are better than what I've heard of their Japanese counterparts. I think your friend just has a stick in her butt.