Despite all the books on leadersip that try to describe the ideal leader, my experience has been that effective leaders have a very wide range of personalities and approaches. However, there is one thing great leaders do have in common.
They are remarkably consistent.
Some are consistently innovative while others are consistently excellent at execution or strategy or brand-building. Some are consistently intense and loud and others are consistently calm and reserved. They have consistent beliefs and reactions to situations. People generally know how this person is going to react to a new set of conditions.
In other words, you know what you can count on with an effective leader. Ineffective leaders change their style and their beliefs in attempts to gain approval from other people. That is consistently an unsuccessful approach.