The only real way to answer this is to say that effective leaders exhibit the behaviors that are appropriate to the situation. This is because there is no one way of being a leader that fits each person and each situation equally well.
There are many different types of behavior that can be important for leaders. Leaders must, at times, be authoritarian. It is sometimes necessary to simply tell people what to do regardless of whether they agree. At other times, it is necessary to be more relaxed and to try to build consensus. There are times to try to get teams together to figure out problems and times when it is necessary to go it alone.
This is why leadership is such a difficult thing. There is no one way to act at all times. Nor is there a perfect way to know when to act in which way. Instead, a leader must be able to determine which leadership style to use in a given situation and must be able to effectively use the leadership style that is called for.