Yeah that's a tough one. Maxie hit on a bunch of 'em I'd say but it seems to me there's a long list of traits that exist in as many different degrees as there are people. Guys like Lombardi or Jordan to some extent are followed in no small part because of their strong personalities, high expectations and willingness to call their teammates/players out on the practice field, in the classroom and on the field/court. At the same time, a guy like Starr achieves the same status without possessing the superior athletic gifts nor does he call them out or get tough with his teammates. Different kinds of respect maybe but they both can work.
One guy can essentially be a bully and it works because he possesses the right combination of other traits to compliment that. Another guy can seem to be totally soft and that works because of his unique combination of other traits that compliment THAT. Then there's the approach that it's perhaps not the leader's traits as much as the leaders ability to be flexible in dealing with situations and personalities in different ways based on the teammates personality traits and the situation at hand.
Now there's a long-winded way of saying I don't have a clue. I suspect intelligence and heart (whatever that means) are two of the stronger determinants.