In the books, he got rid of many Admirals and Captains.
Anyway, for this thread I just have to say:
Don't use the OT movies in a Vader vs fight. Its 1970s, the books on the other hand make Vader more modern.
And don't disclaim the books, its a Movie Character vs an EU character.
admirals and captains = non force users. Vader at his prime even looking at the books couldn't beat Galen. Revan at his prime could not have beaten Galen. Therefore Galen wins.