I consider Aristotle to be the bedrock of the Western traditions of logic, natural science, and individual liberty. I would put in his debt virtually every comprehensible Western philosopher, in particular St. Thomas Aquinas, Friedrich Nietzsche, and Ayn Rand.

In contrast I consider Plato to be the origin of much evil and confusion. I am similarly critical of many Plato-aligned thinkers such as Immanuel Kant and Karl Marx.

Outside of the West, I think Daoism is generally the most insightful philosophic/religious movement, so I would have to praise highly Lao Tzu (if there was such a man) and Zuangzhi.