We have enough Vader-content, in my opinion.
Cad Bane is an interesting character but he wouldn't be my first choice.
I love exploring stories about the Jedi and the Sith but isn't "The Acolyte" basically going to revolve around the latter? So, there would be a show about the Sith anyway.
In terms of individuals, I'd choose either Luke or Mace. On one hand, it would be interesting to see how Luke rebuilds the Jedi Order. On the other hand, I would love to see more content about Mace on screen. He's an interesting character and could be further explored, in my opinion