Say a perfect recommendation system existed. Should it give me what it knows I'll like or challenge me? Should it give me what I ask for even if it's wrong? Sho

Say a perfect recommendation system existed. Should it give me what it knows I'll like or challenge me? Should it give me what I ask for even if it's wrong? Should it aggregate information for me to judge or analyze the content and judge it for me? Is it optimized for me? For the company? For what's best for humanity? And who decides what's best?