It's simple, if you had to chose between joining the good guys or bad guys, who would it be? Note I'm talking about the good and bad as provided by the framework of the story.
For me I can think of a few. For Star Wars there's the CIS in the Clone Wars and the Galactic Empire in the originals. The reason is simple: for he clone wars the CIS was a state which seceded because of the fact that the Republic was just to corrupt and ineffective, and instead of listening to their grievances they simple ignored them. And then what happened? They got invaded. As for he Empire, well, come on. Apart from the blowing up of a planet, they didn't do anything wrong, and even then it was justified since it was a bastion for an armed royalist rebellion that was threatening the peace.
For me I can think of a few. For Star Wars there's the CIS in the Clone Wars and the Galactic Empire in the originals. The reason is simple: for he clone wars the CIS was a state which seceded because of the fact that the Republic was just to corrupt and ineffective, and instead of listening to their grievances they simple ignored them. And then what happened? They got invaded. As for he Empire, well, come on. Apart from the blowing up of a planet, they didn't do anything wrong, and even then it was justified since it was a bastion for an armed royalist rebellion that was threatening the peace.