for me, it depends..but i prefer dubs in a 55-45 margin.
dubbed or subbed, there are really good ones and bad ones...some dubs tend to get so silly and voices can be very annoying....bad voice execution can really ruin the pleasure of watching, i've quit on watchin lots of shows just because of this.
as for subs, really bad grammatical errors and misplaced sentences or phrases are not uncommon...of course everybody commits errors in grammar but somehow it still is understandable...in subbing however, errors like these can be very unpleasant and can be totally misleading. even when you can't understand some of the japanese voices you'll know instinctively that a really bad error has just happened. another problem that i commonly encounter with subs are the fonts, some are too small to be read properly by people without 20/20 vision...and some have really bad color schemes that can make it hard to read...
but if both can be at its best, i would go for dubs...
