Darths before Bane. Whomever created Darth Rivan should be bludgeoned with a sturgeon, and so should Drew Karpyshyn and the others who perpetuated that nonsense.
Ironically, George Lucas likely meant for Bane to be first Darth. Statements from Lucas and the wording of the TPM novelization suggest that the pre-Bane Sith were short-lived and didn’t pose a serious threat to the Jedi. I believe that Lucas meant for the Sith Order started by Darth Bane to be the one that ruled the galaxy 1000 years before the movies.