Raids in SwSh are a joke so it's definitely a lot easier to get candies to level Pokémon there. 4 and 5 star raids in SV are challenging to where you're not guaranteed to beat it, meanwhile.
Of course, not every Pokémon is in SwSh, there are notable holes, so there's still merit to grinding SV raids. The problem is you are expected to have trained your Pokémon in terms of EVs... and the multiplayer has a lot of technical and design problems on top of that.