Both of these leaders are portrayed as ineffective in some way. Richard, although the rightful king, shows himself inconsistent and subject to coercion. Macbeth, not the rightful king, is in turn unable to follow advice or seek counsel, seeking violence as a way to achieve his goals. Richard is an intellectual and fails. Macbeth is a brute and fails. What, then, makes a good man?
Shakespeare never quite answered this question. In Macbeth, we see that Macbeth has a conscience. He evaluates Duncan's leadership and relationship to himself, and vows not to harm him. Lady Macbeth intervenes. She insists that "when you durst do it, then you were a man." In other words, if Macbeth were a proper man, he would commit murder. This portrays masculinity as a display of physical force - except for the fact that this force is what brings Macbeth to his end.
Richard, although leading men into battle, shows a hesitancy to display force. He commits no acutal murders until the very end, which is remarked as his crowning moment (again, suggesting physical force, except that he dies immediately after). Richard prefers thought to action, wanting to "sit upon the ground and tell sad stories of the death of kings." Yet, his intellectual nature does not help him - he is also not a hero. This leaves readers to still wonder about Shakespeare's view of manhood.