In my opinion... Neither.
I think he was a sad, twisted man that did horrible, deplorable things. But I am not sure he is/was "evil", as I hate using that term at all. I see him much the way I see Hitler: a poor soul that got lost somewhere along the way, and made terrible, terrible mistakes. I think they were brilliant men who could have done so much good for the world, but instead used their power and intelligence to hurt others.
If an afterlife exists, I hope he does pay for what he does, but I also hope that-- if possible-- he can find redemption, forgiveness and become a better soul in the end. I think everyone deserves a second chance, and if there is an afterlife or reincarnation or somesuch, I hope he is healed and comes back for a second chance to make the world a BETTER place.