And on topic, anyone found a conceivable reason why joining the Stormcloaks is better than joining the Empire? Or are we still where I left off?
The simple and honest answer is there is no conceivable answer.
That is to say - People would join Ulfric's cause not so much out of reason but out of anti-reason. Endeavoring to rebel against the greatest symbol of reason, the Empire (whom they feel is most directly resp for their suffering), choosing instead to follow instinct (the heart).
For example, some Nords in Skyrim are so disgusted with the Empire and how things are going, that they really don't care about the consequences. They just want the Empire out. Gone.
And contrary wise, those Nords who remain faithful to the Empire would approach this from the opposite angle.
The Thalmor on the other hand, naturally, approach this 'Civil War' with a clarity of thought that gives them the complete edge over any victor. That is to say, the Thalmor have no or very little invested emotion and participate in the Civil War in a very quiet and discerning manner.
Therefore, if you are a Stormcloak, you cannot explain yourself because your passion is what drives you. If you are an Imperial, the same goes for you. Both sides are 'wrong' and are in such dire straights that they simply do not have the luxury to develop an unbiased perspective of this Civil War, as it is part of the Dynastic cycle.
For the Imperials and Stormcloaks, it is about nothing more than survival and nature will award life to the fittest.