So, who do you think would have won the Civil War if the Dovahkiin didn't intervene after Ulfric escaped the Imperials at Helgen?

Unless Ulfric falls into another Imperial trap the war would probably continue indecisively while Elenwen and Ondolemar watch, eating popcorn and high-fiving.

Stormcloaks (I know, big suprise coming from me). A suprise attack was waiting to happen, and all Ulfric had to do was use his bounded arms to uncover his gag (since the imperials weren't smart enough to bind his arms behind his back), which wouldn't be hard to do if you look at his "gag" and let the thu'uming comense. In the attack, they would capture Tulius after they were thoroughly subdued by the voice, and the war would be over. Rewind of Markarth.

You missed a point in the thread: After Ulfric escaped Helgen as it was destroyed by Alduin, not what would happen if Alduin didn't intervene.

The Dominion.