Who believed government should be administered by a group of the best men?

Plato

Explanation:

It is understood, in Plato's logic, that a just government should be administered by philosophers and men of science (which he believes to be the group of the best men). An unjust government is one in which the government is in the hands of the owners and, of course, they do not think of the common good of the city and will undoubtedly fight to preserve their particular economic interests or the military that will carry the city into a state of constant war to contemplate and glimpse particular desires of honor and glory.