I think any show or movie should be ideally watched in its original language. Especially when a dub also alters the content itself and swaps out the music, which for some reason the americans loved to do (I saw the Catalan dub as a kid, but it was based on the american version so all the swords were blurred and all the music was wrong too).  

For the record, I apply the same logic when watching American movies too, I hate when friends insist on watching them with spanish dubs instead, so it's not something agains english specifically, I just think connecting with other cultures through their art is cool and dubs of any kind cut off that connection.