None is wrong, but "look" is best. "Expression" feels too precise. It would be better in the plural: "expressions". However, expressions do not win the world over. It almost sounds like a scientific term. "Smiles" can win the world over, and they are expressions, but "expressions" do not have the emotive power as "smiles". A confused appearance wouldn't win the world over. A "confused appearance" might simply mean that the clothes she was wearing were not very nice, that the colors didn't match, or that she forgot to tie her shoes or comb her hair. "Look" is perfect. It is a nonspecific word that applies to all aspects of the general impression that a person makes.