The Greybeards Trained Him - I'm not sure if this is significant or not, but Ulfric was chosen and trained by the Greybeards to the Thu'um. Let me repeat: Ulfric was chosen and trained by the Greybeards to the Thu'um That has to mean something. To be chosen and trained by the Greybeards has to show some kind of significance, right? He was going to be a freakin' Greybeard! I know Ulfric denied using the Way of the Voice properly, but come on, they had to see something in him.
Ulfric Fought for the Empire - Ulfric left the Greybeards to join the Imperial Legion and help fight in the Great War. He left his training with the Greybeards to fight, cause he wanted to and he chose to. I think that says something. He may have been captured, and he may have become a Thalmor asset, but he still fought for the Empire.
Ulfric Reclaimed the Reach for his People - Ulfric personally shouted the Forsworn from Markarth. He retook the land for his fellow Nords. He was fighting for his country and retook the lost land. If nothing else, it shows he is a brave man willing to fight for Skyrim. And yes, I know the Reach may belong to the Forsworn.
Ulfric Took in Dunmer Refugees - When the Dunmer fled Morrowind cause of the Argonians, they fled west, most notably Windhelm. Ulfric allowed them to stay, and allowed them property, and allowed any refugees who came. Sure, he restricted them to the Gray Quarter, but at least he did take them in, and at least he did not kick them out of Skyrim. Morrowind faced a disaster, Ulfric took refugees while the Argonians invaded - I'd say it's right for the Argonians to live at the harbors. And don't make arguments about him being racist - almost all Nords are pretty much racist and you know it.
Ulfric Values Nordic Lives - Ulfric orders his men to stand down when he is captured by General Tullius. He is willing to be captured and executed before watching his men die before him. This is evident because he gave up rather easily, whereas he could have fought back with his blade and his Thu'um. Ulfric also has second-thoughts before marching onto Whiterun.
Ulfric Challenged Toryyg to a Traditional Nordic Duel - Ulfric challenged Toryyg to a duel. He then defeated him. Roggvir allowed him to escape. And now Ulfric is branded a murderer and Roggvir was beheaded for opening a gate. Ulfric challenged Toryyg in the old Nordic way, nothing about it was a murder. I understand Toryyg agreed with Ulfric's feelings and thoughts, and that he may have 'allied' with Ulfric if he was asked, but Ulfric claims he did what he did to prove a point: Toryyg was to weak to defend Skyrim. That's evident. It's also evident Ulfric values old traditions, even mentioned by Balgruuf himself.
Ulfric Fights for the Nords - Ulfric fights for his Nords, their beliefs and their land. They want to worship whoever they want, specifically Talos. He fights so Skyrim will be free from Empire rule, who allowed the banning of Talos in the first place and let thousands of Nords die in vain. The Empire should give Skyrim their independence and ally with them so together they can fight the Dominion, instead of waste lives and resources trying to keep this unstable region in the Empire.
Ulfric Vows to fight the Dominion - If Ulfric wins the Civil War, he does not imply he will fight the Empire, but the Dominion. So this basically says he does not hate the Empire, he just wanted them out of Skyrim, and once that's dealt with he wants to defeat the Thalmor.
Now just know that I prefer the Empire. I like them and for what they stand for, and I'll always fight for them... but I don't disagree with the Stormcloaks and Ulfric.