Who's The Biggest Villain: Darth Vader, Joker, or Magneto?

I received an ad in my inbox asking that question but really it was just a lead in to a sale for comic books. But the question intrigued me. After all, Batman is my favourite comic book character so his nemesis the Joker is someone I am very familiar with. And I always loved Darth Vader growing up as a bad guy, and even went out as him at Halloween three or four years in a row. So I feel some authority in answering the question: Who's The Biggest Villain: Darth Vader, Joker, or Magneto?

First off, let's get the competition thinned out a little by throwing Magneto out altogether. Yes, he is a little warped in wanting to wipe out normal humans and populate the earth with mutants, but he was traumatized as a little boy and see the prejudice and discrimination of mutants and wants to correct that, albeit in an extreme manner. And Magneto has even allied with the "good guys" on many occasions throughout the years, making him less a villain and more of a competitor or adversary that is more anarchistic in his approach.

Darth Vader is pretty evil, especially once you see Revenge of the Sith and watch him cut down the Younglings at the Jedi temple and then butcher the Secessionists before fighting Obiwan. The dark side of the force indeed. Hunting down the rest of the Jedi between Revenge of the Sith and A New Hope is not very nice either, and the death choke of those officers on his side that disappoint him in The Empire Strikes Back is quite disturbing. Darth Vader is a good villain.
But not the best. After all, in the end of The Return of the Jedi he does turn back to the good side and helps Luke destroy the Emperor by throwing him down the shaft. Redemption comes late in the story and at the end of his life, yet there it is.

Now, could you imagine the Joker working with the Batman for any reason? Heh, not bloody likely! They would probably fight while aliens wiped out the rest of the earth should it come to that rather than work hand in hand. The Joker is not only a crazy criminal, he is a mass murderer on an epic scale. Many people have suffered over the years including the shooting of the original Batgirl which ended up leaving her paralyzed from the waist down. This is one bad dude.

Some might point out that insanity provides some justification and excuse for his crimes. Bah I say, he knows right from wrong, that is why he revels in his exploits. He is not committing the crimes he does out confusion or psychosis, he is doing it for the pure pleasure of the deed. He is evil.

Thus, that is why I pick the Joker as the Biggest Villain. He may not have force mutant powers, but he is evil for the sake of evil.