Ulfric is a man who leads from the front. Leads by example. He makes things happen. He trains his shout.
These other Jarls are a joke! Half of them are kids or following Ulfric like a pack of wolves licking the behind of the Alpha Male.
Take Balgruuf of Whiterun for example.
He barely reacted at all when you told him about the dragon attack on Helgen. He barely reacted at all when he was informed of a dragon near to Whiterun. He barely reacted at all when you came back with the news that you defeated the dragon and absorbed its soul.
You might argue that its because he knows about all the legends and is well educated on the subject. But there is a difference between something you've read about and something that is happening for real right now! Something that hasn't happened in hundreds of years.

) especially the arrogant way the slump in their 'thrones' when they're speaking to you.
The only one I've come across that seems decent is Elesif.