Yes but if we count official what is in the first three movies, (and a lot of people refer only to the movies) vader is just the one who brings the balance to the force. Nothing more nothing else. And he was not even a Dark lord, and he coulded kill an 80 year old guy. And luke lost to ethe emperor, and vader lost to luke, and anakin is vader, and anakin lost to both obi wan and dooku, and dooku was under Sidious, so sidious is more powerful than both vader and anakin(and yoda if what we have heard about episode 3 is true)