As you identify five prominent business leaders and what makes them good business leaders, please allow some of my ideas and resources to lead you in terms of psychology of personality:
1. Donald Trump embodies effective leadership traits. Please note that he appears to be no nonsense, stern, and quite authoritative in his approach, personality, and overall stance toward business and entrepreneurship. He is resolute, often abrasive, in his portrayal on television and in the media as a shrewd businessman.
In terms of psychology theories, you might apply some of Freud's theories about the ego to explain some of Trump's arrogant and egocentric leadership traits. Many of his attributes might have Psychoanalytic implications. Please note how these theorists look at the structures of the mind (Id, Ego, Superego). They argue that the "mind has an internal structure -- three parts with separate motivations: Id (irrational and emotional part of the mind); the Ego (rational part); and the Superego (the moral part)" (http://www.wilderdom.com/personality/L8-1MajorThemesAssumptionsPsychoanalytic.html).
Another idea is to examine Trump's style in terms of Behaviorist theories since he is firm and authoritative in his style. Please note that "Behaviorism refuses to acknowledge the internal workings of persons. In the mind of the behaviorist, persons are nothing more than simple mediators between behavior and the environment" ...
This posting applies personality theories to real world leaders as models.