I generally never think that dubs are bad unless they're from 4Kids. This isn't a "I hate the actors" thing (except for David Moo), its more of a "I REALLY HATE AL KAHN AND THE 4KIDS WRITING STAFF THING."
In any case, I think that FUNimation is the greatest dubbing company in America given the fact that they have actually dubbed the OP's before which is a major "Good job" in my book (Though the dubbed version of "Sakura Kiss" hurts my ears. A rare miss). Yu Yu Hakusho and Full Metal Alchemist are two shows in which I believe that they have surpassed the actual original voices.
Also, I understand 00 since that dub is incredible, but what the heck is so great about Wing, SEED and DESTINY's dub? The characters sound insanely flat and Kira's VA sounds like a complete surfer dude. (Remember "Kira Yamato, Freedom, LET'S DO IT!")
Also, I don't know if anyone has seen the dub for Law of Ueki but...seriously don't. In fact, I hate to be advocating fansubs publicly but, seriously find the fansubs and watch them. I'm not claiming to be a major in Japanese or anything but I do know what dubtitles are and the subs on the Law of Ueki DVD's are completely dubtitles.