The eternal debate in anime fandom. Do you watch it in the original Japanese with annoying English subtitles cluttering up the screen, or do you watch it with American voice "actors" hamming it up and stumbling over Japanese names? And if you like the one that I don't, what the hell's wrong with you?!?
Ultimately I think it's a moot point. If the show is popular enough to make it to the States, then the DVD will have both subbed and dubbed versions available to watch, so what's the problem? I think it may have to do with plain old self-centeredness. How dare you like something I don't? Of course, you don't really get a choice when it's on TV, and most new anime fans (myself included) enter the subculture through dubbed televised shows. I think this is why dubbed anime gets so much flak: It's all that's available for many people, and most of it terrible. I'm sorry, but it is. The American dubbing industry can't afford the best cast and crew (like Central Park Media), or just doesn't care enough to put in the effort (like 4Kids Entertainment).
Which segues into my next point, which is my personal preference. Well, truth be told, I really don't have a preference -- I take it on a case-by-case basis. Like I said, I think most dub jobs are crap, but there's the occasional gem that really shines out, like the American productions of Cowboy Bebop or (my favorite dub) Fullmetal Alchemist, not to mention Disney's star-studded dubs for Studio Ghibli's films (Princess Mononoke, Spirited Away, Howl's Moving Castle). Even if the quality of the dub ain't so hot, I occasionally get a kick out of it anyway -- for instance, I enjoyed the over-the-top old-school dub of Record of Lodoss War (I will forever hold a torch for Lisa-Ortiz-as-Deedlit-the-Elf); and while the acting on Azumanga Daioh was a little choppy, it was apparent that the voice actors loved their characters, and that gave it a real charm.
There are still instances where I prefer to watch anime with subtitles. Contrary to popular belief, I don't feel that Japanese voice actors are better (or worse) on the whole than their American counterparts, but when you're not fluent in the language, you just don't pick up on poor acting as easily as you do in your native tongue, and that helps when you're trying to immerse yourself in the show. Furthermore, generally speaking, I like seeing foreign film in the original language, and anime is no exception. A dub also really isn't an option when you're viewing the newest series -- last year, I followed The Melancholy of Haruhi Suzumiya and Ouran High School Host Club (both of which I really ought to write posts about sometime) as each episode came out in Japan, so of course there was no dub yet. Of course, by the time I caught a clip of the American Haruhi Suzumiya dub, the original version was ingrained into my mind, and listening to American voices coming out of the characters' mouths just felt wrong.
One other factor, which is totally a footling point, is that it just creates an odd dissonance for me when characters who are Japanese are speaking English. It feels weird to me. On the other hand, if an anime series is set in, say, London (Hellsing) or the characters are all obviously Anglophones (Fullmetal Alchemist), hearing them speak English just feels more natural.