I'd choose Socrates – even if he were to be a fictional character created by Plato. His death has an Archetypal truth imbued in it about how wrong we can be when we enter group-mind. True two thousand years ago as much as it is today in our current socio-political climate.
Yes, there are things I find him guilty of, most critically, being so hellbent on his approach to educate others through public self-ridicule. In aiming to be the ideal, Socrates failed to find a compromise that could have led his contemporaries to recognize their own limitations without it being at the cost of his own life.
But, in being the ideal, he left us a sharp example of what to be and what not to be both as individuals and as a people.