Ok by spoiler lite I want people to point out reasons for their decision BEFORE they actually played the quests out.
My character hasn't chosen yet. He already beat the end-boss, but I may continue just to see how high level I can get I guess. And I also want to see more content.
Here's what I see:
Imperials:
Less radical status quo and less instability/war
Big jerks when they behead people
In bed with the Thalmor who are the most vile people I have met so far
Tried to behead my character
I could probably add more after some thought
It could be good to be in bed with the Thalmor because you should put your enemies closer than your friends or so the saying goes...
Stormcloaks:
Racist and my character is Mer, an Orc
I would be stormcloak but I am not sure how far the racism permeates the organization. Is it the KKK or is it just a few meat heads in the ranks.
Right Speech has four aspects: 1. Not lying, but speaking the truth, 2. Avoiding rude and coarse words, but using gentle speech beneficial to the listener, 3. Not slandering, but promoting friendliness and unity, 4. Avoiding frivolous speech, but saying only what is appropriate and beneficial.
I also got the impression that the Stormcloaks are more "you're with us, or against us!", while the Imperials, in general and for the most people, provide stability and security.
I choose the Imperials, because I'm not too keen on people like the Stormcloaks who's main or only political argument is "Ethnic origin is THE basis for a nation, just because!"
I picked imperials simply because they seemed far more pragmatic. Starting a war against the Thalmor seems like a good way to provoke them into committing genocide. Also, if you played the main quest, you might remember that Ulfric has some rather, eh awkward connections.
While the imperials did try to behead your character, depending on the back story you made up, they might have been justified. Also, lets face it, you don't have to be very selfish to think that provoking the two most powerful empires on the planet by siding with the cloaks is something to be avoided.