Replying to NS'ers with philosophy experience, help out really quick please

So I need to write a paper comparing 2 different philosophers' ideas on a specific topic of human nature. The philosophers I can choose from are
Aristotle
Plato
Aquinas
Descartes
and Augustine
and the list of topics to choose to compare/ contrast them on are:
relation between mind and body, immortality of the soul, possibility of knowledge, the object of knowledge, free will, virtue, happiness, the problem of evil.
Any suggestions on which topic and which 2 philosophers it would be most practical (and easiest) to compare/ contrast on which topic? +major K if you can help out, thanks.