Can we be a little careful about fansubs, as technically they are pirate (unauthorised copies of coprrighted materials).
What I will say is, that given the choice between a translation where the translators (have usually) got access to original scripts (often for the entire series) AND can, if need be contact the original writers for clarification, or someone who is doing the translation by ear alone based on what has been aired so far, I'll tend to go with the pro's
IIRC Jonathon Clements articles on translating are quite interesting when it comes to the differences between translations (pointing out that even a technically "perfect" translation can be wrong if the person doesn't know the full context and have a good working knowledge of both languages including the background being certain phrases).
Over localisation can be an issue, but personally if the choice is between say two jokes,one a literal translation of the Japanese, that doesn't work without explanation in English, or an English equivilant, the one that works naturally preferred option, as long as it doesn't change the feel of the episode (IE in Azumanga Diagh when they play the word games etc, it makes sense to translate that in a form that works in English where possible, rather than stick to the Japanese and lose how the game works).
I'm very much a physical man for my content - as can be seen by the lack of remaining storage around my computer and DVD players