I sometimes can't keep up with the subs and have to pause and go back. It's really annoying cause I do wanna miss anything. I've been watching a lot of boku wa tomodachi ga sukunai and it's hilarious, but sometimes I miss jokes because of the subs going too fast.
I prefer subbed since, as many people have pointed out, the original voice acting tends to be better. I do, however, prefer dubbed in certain cases where the voices are fantastic. Ghost in the Shell comes to mind for this one. I absolutely love the variety and quality of the voice acting there. Death Note also seems to have some quality English voice acting.
The biggest issue with subbed anime is that the translation can be a bit different depending on which source you get it from. I suppose the faulty translation problem can apply to dubbed anime as well, but it's official and the fans don't have to worry about getting the best version since there aren't any others.
Dubbed anime isn't generally bad per se, but it always plays second fiddle to the Japanese voices because they fit better in the scene 99% of the time. Not to mention that this is a Japanese forum, thus most people will prefer the sound of that language XD
Though I do prefer subbed anime far more than dubbed, I CAN say that there are definitely anime out there with fantastic English-speaking voice casts which I DO prefer. The English-speaking cast of Ghost in the Shell would be my favorite example -- Most dubbed versions of anime which have a considerably large budget tend to have much more quality than those which don't, so I can't say that subbed is always better. It's just the most anime aren't backed with nearly the sort of budget they'd need to hire on decent voice actors.
The weeaboo side of me likes to hear Japanese more than English simply because I like a more "pure" and unchanged experience, but there are definitely cases, such as with Ghost in the Shell, where there is a unique level of quality in the voice cast. One thing I must say about Japanese voice actors is that it can be difficult to differentiate between them at times. It becomes far easier to hear the difference between similar voices as you learn Japanese and gain an ear for subtle differences in accent, emphasis, tone, and so on, but I think that it is much easier to differentiate between characters who speak your native language because it is easier for you to understand the nuances of your language that each individual character might portray, at least insofar as the voice actors of those characters are able to illustrate.
Subbed. Ten+ years of watching anime subbed led me to learn a lot of grammar and vocabulary just by matching what I heard with what I knew was being said and seeing the patterns make themselves visible to my inner eye. The only thing anime can't teach you is to read&write, which means that you still need to pour hours upon hours into learning kanji.
My only problem with the dubbed versions is that the major producing english companies keep re-using the same actors over and over again and they are not very good sometimes. I know this happens in the japanese versions too as it would be impossible to keep using new voice actors and actresses and some are just very popular but I guess in my own language it is a bit more distinct and recognizable.
I prefer them definitely subbed (if anything) but I think it depends on wether you have seen them in english before. Just like Joseph said, there are some movies and series I grew up with on which I prefer the german. I think it has a lot to do with the fact that I got to like them in this language and so I prefer it. Just like I am now watch the original (japanese, english, etc.) and cringe when I hear the german dubbed version.
Definitely subs! Despite the fact that my Japanese is poor and I understand only like 10%, the voice actors are perfectly fitted and it's such a wider and richer experience than watching the same anime dubbed.