What did Socrates, Plato, and Aristotle think of democracy?

Not a one of them was in favor. Well, it's hard to tell the views of Socrates and Plato apart, as the former left no writings. But Plato is certainly not for democracy; his Republic portrays a sort of meritocratic oligarchy, and his associates were involved in oligarchic activity. Aristotle is also not for democracy; he prefers a mixed constitution and viewed democracy and tyranny alike as corrupt forms of government.