In my opinion I think One Piece is a better story and manga, but its still one of those shows that I think is going on way to long. An anime/manga needs to be really good and keep it fresh if its just going to go on forever.

Also, comparing different shows based on their english dubbing is ridiculous. Watching the show with the original japanese voice actors is going to give you the most complete experience. I never understood people who actually prefer english dub.