The top picks outside of lane to counter Olaf include Aphelios, Lucian, and Caitlyn. These picks are all great at countering Olaf with decent win rates over 55%. Even if these Olaf counter picks are not used in the same position as you, it's not smart to play him into any of these matchups. They will very likely crush Olaf.
Conversely, if the opposite team picks either Heimerdinger or Naafiri, you should strongly consider choosing him, as he easily destroys these champs with win rates over 53% against each ofthem.