Oh this is an easy answer for me.
Subs, hands down. There are very few dubs that can actually pull it off nicely and truly capture the character, one of these Anime is actually the widely known [I]Full Metal Alchemist[/I]. Every character in the series is brought to life by the cast, as is [I]Ghost In The Shell[/I].
I can't take [I]Naruto [/I]seriously witht he horrible dubs, I mean the person who is the voice over for the troll that is Naruto is a huge smoker lady; sorry but I can't ever take that seriously.