The original Japanese audio is superior to the dub for a lot of reasons. Actually this debate has been debated to death, and a lot of people will disagree with me, so your mileage may vary..

1. The dub sounds wrong, cringey and unnatural to me because I did not grow up with it, and because I have an inherent bias - it's japanese media. It ought to be watched in Japanese. Do I know any japanese? some. but it is not necessary to enjoy the sub
2. The sub offers a more authentic feel, you are getting what the Japanese author and director intended, down to the last word and in every line. There are even unspoken cues sometimes and meaning that is just completely lost if you try to translate it to english
3. sometimes the dub replaces a line for convenience reasons, which hurts the story if you are a purist sub-enjoyer
4. japanese pronunciation sounds better than the english pronunciation of non-english (JAPANESE) words. example - YOU + ME + CHEE + KA is meant to be pronounced YOU - MITCH - KAH. In MANY cases there is literally no difference "Bankai" "Hitsugaya" "Ichigo" "Orihime" sound nearly the same in english as they do in japanese - just to be fair.
5. the japanese have an INSANE work ethic and voice actors take serious pride in their work and the industry is extremely competitive. There is heart and soul you can feel put into the original japanese audio. You can, in some cases, lose this when it goes to a dub. this is more often seen in spanish/german dubs - the voice actor just reads his line and moves on. this point, summarized, implies "japanese voice actors are superior" but I'm not saying every english voice actor sucks, i hope you understand what i'm getting at though. It's not like Kubo is sitting there with the dub actors telling them how to deliver their lines effectively in a language he doesn't speak, you know what I mean?
   

Sub is better. It's okay to disagree with me