Darth Bane is one of the most significant Sith Lords in Star Wars, but Revan from Star Wars: Knights of the Old Republic proved to be even more important to the Sith. While Bane's Rule of Two is still an integral aspect of Star Wars canon, both he and Revan had detailed histories in the Legends continuity, allowing Revan to influence the Sith just as much as Bane did. Because Revan is confirmed to exist in canon, it's possible that his history from Legends still applies and makes him an essential part of Sith history.
Although Revan returned to the Jedi Order in KotOR's official ending, this made him even more important to the Sith. He became one of the most memorable Star Wars characters to have walked both paths, something that Bane never did. This may seem like an advantage Bane had over Revan regarding the Sith, but Revan was still more important, with his story greatly influencing Bane and his line of Sith Lords.
