Subs because when the sub is decently done, you'll get more outta the anime. (they don't hafta do any lip-sync stuff so they can do more direct translations)
For those who think that you'll miss things because you're reading subs, you won't. At least not if you can read at a moderate pace.
The original voices tend to fit the characters better, and IMO it is more enjoyable.
There are some instances when dubbed is alright, but hentai is definately not one of them.