Palpatine must be glad for the Rebellion though. He spent years manipulating everyone during the Clone Wars and probably had fun doing it. So what next? Where's the fun when you control everyone and have the most powerful army in the galaxy? I feel like without the Rebellion he would have lost purpose and motivation. Back on topic though it was like a human and Sith empire in a way. Palpatine was a Sith but he also hated aliens if I remember correctly (hence no aliens in the Galactic Empire in the films.) I'm sure there were aliens in Imperial positions but not many.