The evaluation is based upon how often did American government policies strive to achieve peace, freedom, human rights, and prosperity, both at home and around the world, vs. how often were US policies more focused on expanding the profits of American Capitalism, both at home and around the world.
Some names come to mind immediately who represent the later: the Dulles brothers, Robert McNamara and General William Westmoreland, Henry Kissinger, Oliver North, Alexander Haig, Dick Cheney and Donald Rumsfeld, and now everyone left in the Trump Administration.
There have been many American leaders and diplomates who attempted to counter balance the efforts of those on the list above. It seems to be a constant push and pull.
What does America value most, profits or people? That remains the unanswered question.