Can't comment too much on the English dubs, but those that I have heard weren't that bad. Grave of the Fireflies is a must see, as is Nausicaa and Princess Mononoke for those who haven't seen them yet. Howl's, Totoro, Spirited Away, Porco Rosso, Pom Poko, My Neighbours the Yamadas and Whisper of the Heart are pretty good too, but having said that I've yet to see a bad Ghibli film (Nope, I haven't watched Earthsea yet, I'll reserve judgement on that for now).