John Maxwell
Maxwell is inspirational because his explanation of leadership and its implementation is very easy to understand. He also inspires you to be better in every phase of your life.
Allan Lind
Dr. Lind's unique understanding of leadership and its implementation is best described through his and partner, Dr. Sim Sitkin's Six Domains of Leadership. It provides a critical understanding of the phases of leadership and how to successfully approach them.
James McGregor Burns
Perhaps the founder of modern leadership discusses the study effectively and focuses on the interpersonal relationship between those who lead and those who follow.
I also have several blogs on leadership that are very interesting.