Bane can be recognized as the weakest of Banite Sith dynasty(excluding Maul, Millenial and some other unknown exceptions.Dooku is hard to be recognized as creation of Banite system, because Sidious has never wanted make Tyranus stronger than himself, but i think he has good chances in the battle with Bane). So Bane would go after Zannah and Cognus and many unknown Siths.
What about Starkiller... He's more powerful than Vader and his Force potential is like Skywalkers' one. He had a little experience compare to Dessel, but his Force level... So, if we take Orbalic Bane, I'd say Starkiller could overwhelm his Force shield with lightning and Orbalisc will kill Bane. In case if Bane would manage to resist, Starkiller can destroy him with hitting head( orbalisc armor weakness). As we can see in Rule of Two novel, Bane is amazing lightsaber duelist, but Jar'Kai masters can overwhelm his defence.
Dynasty of Evil's Bane can't be easily killed by lightning but his stats aren't so impressive as Galen's.In lightsaber Starkiller prefers Jar'kai + Juyo, i agree that Bane could learned how to resist this style by final novel of the Trilogy, but anyway...
As for Force powers, Starkiller is just better if even take Bane's experience.And we shouldn't forget that Dynasty of Evil's Bane has weakness caused by long time Dark Side using...
I don't say Starkiller would easily defeat Bane, no. I think it will be close fight and Galen can even get hardly injured. In my opinion, Bane's level is close to Vader, but a bit lower.
Dooku would win.
He's got way more experience with stronger foes than Bane. Dooku beat The Chosen One and Obi-wan Kenobi. The second time he beat Kenobi while fighting the Chosen One. He also is seen multiple times besting Grevious and Ventress in duels/training things.