Which of the "teams" do you think should win? Brutus and Cassius or Octavius, Pompey, and Antony? Think about their individual characteristics as well as what they have going for them as a "team". Which would you rather have in charge? Why do you think that? Then find reasons in the play to support what you're writing.
Set up your response as a compare and contrast. Using a Venn diagram, analyze Pompey as a ruler v Caesar (You can expand this approach to include Brutus, Antony, Cassius, etc.)
Look at historically documented facts. THEN look at how Shakespeare portrays these men. Even with very few lines, Shakespeare sets the framework and tone of the play. Don't GUESS in your paper. Carefully list the positives and negatives of each potential ruler. Look at these traits: Leadership skills, military skills, speaking skills, etc. Then compare and contrast each person your teacher has asked you to consider. Don't use questionable sites. E-notes has great historical references!