Darth Vader has widely been accepted as one of the most powerful Sith Lords in the Star Wars Universe, with his death being a massive blow to not only their order but also their overall hold on the galaxy. This produced a massive power void as well as an imbalance in the Force. However, the recent Ahsoka series demonstrated that the Nightsisters could fill the role once inhabited by the Sith, with the Emperor’s first apprentice having already proven that the children of Dathomir are the true inheritors of the powers of the Dark Side.
Source：https://www.cbr.com/star-wars-darth-maul-ahsokas-nightsisters-sith-successors/
