Personally I'd go with the sun also rises. The dual aspects of what it means to be a man as explored respectively by Jake Barnes and the main character are fascinating when you get down to it. The swimming scene as contrasted with the bull fight give insight to power vs transcendence. The exploration of what it means to satisfy the body or the soul are still relevant today.
I once wrote a paper comparing Rises to Faulkners sound and the Fury. I think it was my first A.