Started playing Skyrim, admittedly late to the party.
I have yet to see someone who actually sides with the Imperials a lot or prefers them over the Stormcloaks, and I do not know why. I was imagining some noble, brave warriors fighting for freedom. Nope.
The Stormcloaks, and their warmongering leader Ulfric, have not done any good for Skyrim as far as I can see. Granted, I haven't seen much. Just in the short time I have been playing, though, I have found so many flaws with them.
If I understand correctly, the rebellion started because of the outlawing of the worship of Talos. Talos has a large following in Skyrim, and many Nords who fought for the Empire feel betrayed. OK, I can get behind this even though I am not big on religion. They should be able to practice what they wish.
But only what they wish.
The Stormcloaks are a band of racists and warmongering barbarians. They seek freedom, but only for themselves. The Gray Quarter is an example of this.
"I fight for my people impoverished to pay the debts of an Empire too weak to rule them, yet brands them criminals for wanting to rule themselves! I fight so that all the fighting I've already done hasn't been for nothing! I fight... because I must."