Concerning your question about the two social and economic classes featured in The Outsiders, this is really a question you have to answer for yourself. My answer can't really help you. My answer reflects my background and my likes and dislikes, not yours. Here are some things to consider or to be aware of.
First, the story is told from the point of view of Ponyboy and company, of course, since Ponyboy is the narrator. The reader generally identifies with a story's point-of-view character. So it is natural that a reader might like or at least identify more with Ponyboy, etc.
But your assignment is really even easier than that suggests. All you have to do is give your opinion of one of the two groups. Just ask yourself some questions about whichever group you choose:
- Who are they and why do they do what they do?
- Are their reasons justified?
- What emotions do they reveal? Or what emotions do they hide?
- Did you find yourself hoping they would win or lose the rumble?
- How realistic or life-like are they?
- What exactly is your opinion of them?
Answering these questions for yourself should make your assignment really easy. As long as you've read the book you should have no problems.