The voice acting is almost always vastly better in the original language. The creator of the work spent significant time and money finding the right person for each role and then spent even more time working with them to get the performance they want in every scene. This is especially true in Japan since voice actors are more of a big deal there than in the US. For the dub, that kind of care isn't usually put into it, and even when the company producing the dub does put some effort into it that only reflects
their desires, not those of the original creator.
That's why you so often get a very recognizable (and annoying imho) "anime dub voice". It sounds extremely unnatural. I can often tell if something has been dubbed from its original language just by hearing a few spoken lines of dialog! That shouldn't be possible, but it's obvious.
The other main problem I have with dubs is that they are not faithful to the content of the original work. Sometimes they rewrite parts of the script to avoid mouths not matching up with English voices, or to limit the amount of work needed to edit the mouths to match. Sometimes they rewrite the script entirely!
They also tend to make all kinds of totally needless changes. They'll often censor content and dumb down the script (typically by over-explaining everything). They almost always make changes to localize it by removing/replacing cultural references. One of the things I enjoy about consuming media made in other countries is that I get to learn things about those cultures. I like to see artistic works that come from a non-US perspective. I don't want that stripped away.
If you're looking at art made in another language, the ideal situation would be to have mastery of the language it was written/performed in, and that you'd have all the cultural knowledge to fully appreciate the many careful and deliberate choices the creator made. Most of the time, that's just not possible. Translation itself is a lossy process. It means that for you to enjoy it at all, you have to accept that some things are lost. The goal then, should be to retain as much of the original work as possible. That means subtitles and original voice acting. If you watch a dub you are not getting the work the creators envisioned and labored to bring into the world. You're getting something very different and much farther removed.