Seriously, I did the Stormcloak line first, thinking "why should I help the Imperials when they tried to lop my head off?", though after attacking Whiterun and listening to what the Jarl had to say, my view of the Stormcloaks shifted. I play a Redguard and it struck me that the Stormcloaks, though they may have some right, are a bunch of racists douchebags who want Skyrim back for themselves just so they can continue long-dead traditions and get all non-Nordic races out of their nation. Seriously, at least the Empire makes the world a better place for everyone. If you talk to the people of Whiterun after the Stormcloak dictation, you discover that everyone, even the Nords, preferred the Empire too.
TL;DR, Stormcloaks are racist bastards who care about nothing but themselves.