Subbed, as the voice actors are better some 80% of the time in the original language, anime included. Some things are okay in English but since most have the habit of using the same few people over and over again to voice all kind of characters who just don't really fit right, often times regardless of how they sounded originally.
My two examples are that I liked Scott McNeil as a few voices (that all sound the same, just with different accents, as most will attest to) in Reboot but I can't say I've enjoyed him as anything in dubbed anime aside from one exception (Gundam Wing, and yes, I know the dubbed voices were...odd and kind of not-quite-right most times, but it was one of my first gateway series, like Escaflowne - that had similar issues - and I still like anyway).
The other is that when I watch something like...say, Bleach, in the original, with subs, I appreciate the characters a lot more, and tend to get actual things like emotion, intent, etc, etc, even if I don't speak the language. You get used to hearing it too and it's kind of pleasant. In many cases, with good subbing and good voices, it's just a huge treat. I don't follow most series that transition, but the ones I have usually either suffer massively from voices (and/or sensoring, and/or story modification/obliteration) or just are about the same, though still not really a spellbinding/overly interesting series (Inu Yasha, for example).
