These are just samples; you may argue for one of these if you wish, but you aren't restricted to them. Another good place to look is in the list of reading response papers; they give a decent list of topics we've studied and suggestions about things you might want to argue about.
In this paper, I will argue that Socrates in right when he thinks that the only thing that matters of happiness is the health of your soul, but that (contra Socrates) worse people are able to harm the soul of a better person.
In this paper, I will argue that Socrates' objections against Euthyphro's defintiion of piety as what all of god love does not successfully refute a Divine Command Theory of ethics.
In this paper, I will argue that Annas is wrong to think that the Myth of Er afterlife is 'pessimistic.'
In this paper, I will argue that Socrates' depiction of the 'return to the cave' is inconsistent with his insistence that it's always in your self-interest to be a just person.
In this paper, I will argue that Sachs is right that Socrates' argument in books II-IV of the Republic is fallacious.