If you were in favor of book-banning, and in a position to ban books, what books would you ban?
“I would never ban books” is not an answer to this question. That’s just counterfactual resistance, a distinctive symptom of the intellectual immaturity of beginning philosophy students. “I cannot honestly answer the question because I would not recognize a person who would ban books as me and would have so little continuity with that person that I cannot be expected to have any insight into that person’s preferences,” is a sound point, but still completely lame.
I’ll get you started: Battlefield Earth.