Pre-wraith Dukat and Winn are probably the most realistic villains in the Star Trek universe.
Dukat was never a good man. He was a ruthless tyrant. He was willing to be a little nicer to the Bajorans than the others...so long as they accepted their 'place in history' as their slaves, and had sex with him, understanding the kind man he really is. He had a good reparte with Sisko and Kira...so long as they were always taking him seriously.
But, he was not a sociopath. He was able to experience genuine feeling for other people. He probably actually loved all the Bajoran women he took as consorts, but those emotions came from a place of absolute belief in his superiority, loving them like a slave master claims to love his slaves. But however real those emotions may be: They never affected his actions. Only his explanation for his actions.
He's like an actual tyrant, behaving in much the same way third world dictators behave in real life, and doing so with the same attitude and cognitive dissonance.