Machiavelli's question still resounds. Upon this a question arises: whether it be better to be loved than feared or feared than loved? His answer was best to be both. Then he added that you can't make someone love you, but you can make others fear you. To this he added a warning to avoid being hated, implying that to be feared and hated is worse than not to be feared.
The issue that Machiavelli discusses is a complex one that still reverberates. A more modern conservative take on the issue is: "A leader should be strong", with strength being equated to feared, and weak being equated to loved. A more modern liberal take on the issue is "Tyrants are worse than civilized leaders", with tyrants being feared and civilized being loved.
Like Machiavelli, I agree that the best leader should have some aspects of both - be both strong and civilized, while avoiding the extremes of weakness or tyrannical.
That said, I see it as a continuum: Tyrant - Strong - Civilized - Weak. If you are between Strong and Civilized, you are doing a good job. If you get to feared you become a Tyrant, or too Loved, you become Weak. Strength flows from fear of being beaten, civilization from bravery and a willingness to take a chance.
So, how does someone identifying where a leader is on the spectrum.
First, remember it is a continuum. In addition,how strong/civilized you should be depends in part on what you are dealing with. If you are dealing with a Hitler/Stalin, you need more strength then with a Chamberlain. That means if you are the strongest political leader of all the countries you have issues with, that means you are very likely to be too strong - a Tyrant. Similarly, if you are the most civilized leader of all the countries you are dealing with, you are likely to be too weak.
The United States for example has been acting very strong for the past 10 years. We got scared and went for strength. This is a common reaction - fear leads to a desire to be feared. Civilization requires bravery.
Gitmo, multiple wars in the middle east, etc. As such, the US President has to watch out and to avoid being a tyrant. Right now, he is being forced by congress and internal politics to keep Gitmo and to do military trials.
Second, remember that secrecy is the friend of the extremists. If you are afraid of what others will think of your actions, then you recognize that others think you are wrong and that you think their might be bad consequences for you. This is a huge warning sign of extremism - both tyrants and weak leaders don't want others to know how tyrannical or weak they are. In addition, a true leader will care more about doing what is right than about the personal consequences. While sometimes a government needs to act in secret - that should only be done to allow the action to succeed. If any part of the desire for secrecy is to protect the people from moral judgment, that is a huge warning sign of the Tyrant (while weak leaders want secrecy, usually they are too weak to keep it.)
Third, remember that the desire for Strength comes from fear, and the desire for Civilization comes from bravery. So you need to ask yourself what are you afraid of (or not afraid of). If logically the thing you are afraid of is ridiculous, tone down the strength. If logically you are being overconfident, then stop being quite so civilized. Ideas like "my opponent can not beat me" = weak. Ideas like "my opponent, even though he lives in a cave and I live in a high tech electronic command center can strike me and I can't hurt them" = tyranical.