I never saw Roanoke and have no intention of seeing it, but of the four full seasons of the show I did see, Bates's performance as Madame LaLaurie was the best of that run (followed by Rabe and Cromwell in Asylum) and fully deserved her Emmy victory, even if I hated how her character's arc went after the midseason break.
I really liked her in Hotel and Freak Show (she and O'Hare single handedly made the former watchable). A hell of a lot more than Roanoke. Coven was comfortably her time in the sun though. I was so sad at the time Bassett seemed to be the one most people were talking about.