If we take into account the quote stating how dangerous he is in legends due to his superhuman ability to adapt to different styles of lighsaber combat quickly and exploit them, he has a pretty good shot at all of these guys with Dooku being the most susceptible to strength-based attacks. If he takes down Maul, it'll be to exploiting his mental susceptibility rather than anything physical.
In the film it's also said Yoda and Ben believed Luke can kill Luke, and there only doubt for Luke was Luke himself not wanting to kill Vader. Luke also held back as well, and 2 times Vader took a swing at Luke that if Luke did not stop would have died, so the emotional conflict within Vader isn't as extreme as people make it out to be.