Quote Originally Posted by chaika

Maybe you could measure evil by the number of human beings killed by each of them?
In which case neither would win.

The difference between Hitler and most other evil dictators is the way the Nazi's committed their crimes. They took the idea of Gulags and other similar institutions and turned them a notch up to not only slaughter people en masse, but to also profit from these murders in an organised way never seen before.
Also, peoples perception of mankind slowly began to change after the war due to the increase in studying the 'Nazi phenomena' by psychologists, sociologists etc. For the first time in humankinds rather bloody history it became accepted that these evil people were actually no different from the rest of us and we all have the capacity to be evil given the right stimulus. Many people wanted to disagree as this didnt leave a good taste in the mouth of ordinary people and acedemics alike, but eventually these facts were accepted.
So Hitler will always be a name on the list of evil people and rightly so. But I dont think you can, or even should measure him, or anyone else, against each other.