I prefer Japanese voices with English subtitles, especially if there is lip syncing involved. Japanese characters say more with less text than English characters, but when it comes to speaking it is English that says more with fewer syllables. When lip syncing, the writers and translators need to find a way to fill up the extra syllables and this is incredibly hard. Immersion is ruined for me when this is not done smoothly, and it almost never is.
Secondly, there are certain Japanese-isms that just don't translate well into English. I can't think of many examples off the top of my head but 'even if you say that,' comes to mind. In English we just say "but," and we know the speaker is going to contradict another. There are other ways people might say it in English but none of them are 'even if you say that,' which is why it sticks out. Another is the repetition of characters' names throughout dialogue. When things that are unique to the Japanese language and culture are said out loud in English, it takes away from my immersion in the story.
Also, sometimes English voice actors are just bad. Maybe the Japanese voice actors are bad too, but they sound alright to me, someone who doesn't know the language.