I dunno guys. I really dislike the whole evil empire just because the leader is evil thing. To me it seems overly childish. Morality isn't even shades of grey, it's infinite colour.
The Empire was evil because the Empire was Evil. Sure some people in it may not of been, but the group as a whole was. Why? Because that's what George Lucas said.
Star Wars was/is a space opera and one of the hallmarks of that always has been black and white morality. The good guys are Good, the bad guys are Evil, and that's just how it is.
Take the opening crawl of A New Hope...
"It is a period of civil war. Rebel spaceships, striking from a hidden base, have won their first victory against the evil Galactic Empire."
It says it right there, the Empire is evil, this is not actually open for debate. While some may prefer a more nuanced approach or villain, that is not what you got with Star Wars.