Some dubs are really fucking bad, most aren't great, but they are getting a lot better.

Even notably good dubs (TTGL, MHA/BNHA, etc.) are usually worse than the subs just because of how distractingly weird some of the dialogue can be. It's unavoidable because the dialogue has to match the preexisting lipflaps because editing footage isn't allowed (especially these days. Back in the 4Kids days it was a different story).

There are certainly anime where I prefer the dub (Dragon Ball, Cowboy Bebop, Baccano!, FMA: Brotherhood, etc.) but that's like 50% nostalgia.

I don't watch the Pokémon dub any more. It's shite. When 4Kids lost the rights back in the Hoenn days they changed the voice actors so I have no nostalgia for the current squad, and I genuinely don't like Sarah Natochenny as Ash. I'm sure she's a super nice, talented person but I hate her Ash. Can't get passed it.

Also, and this is a big deal, they don't have the rights to some of the music somehow so they just cut it without replacing it. In the original, Japanese dub you'll have this climax to a big battle where he OP is playing and the Lyrics kick in as Greninja or Pikachu or whatever launch their final assault. Y'know, that hype shit shonen's all about. In the English dub the scene just plays without music and it fucking sucks. They don't even replicate the same thing with the English OP. The minimum expectation. It's just trash.

People rag on 4Kids for good reasons but at least they gave a shit about making a good product, even if it wasn't faithful to the original work. The Pokémon Company dub is just so fucking phoned in it's actually painful.