Of all the Nords in Skyrim, who would you elect High King of Skyrim, of that power was given to you?
Ulfric Stormcloak is strong enough, devoted enough, and knowledgeable enough to be a suitable High King, but his hateful demeanor towards non-Nords are what make me disagree with choosing him.
Brunwulf Free-Winter would be a good candidate, especially since he is a war veteran and because he is more 'nicer' towards the non-Nord races. He seems to know what's right and what's wrong. But after hearing of his distaste for war, I would fear he would be hesitant to strike at Skyrim's foes.
Lastly, the other candidate would be Balgruuf the Greater. Balgruuf seems like a good leader and good person, but his denial of choosing the Empire or Stormcloaks makes me think he is indecisive.