The greatest picks globally to counter Zeri include Elise, Naafiri, and Volibear. These picks are all great at countering Zeri with high win rates over 59%. Even if these Zeri counter picks are not chosen in your lane, it's not smart to take them into one of these matchups. They will likely crush Zeri.
Yet, if the opposite team brings either Rumble or Kassadin, you should seriously consider picking them, as they easily wins against these champions with win rates over 55% against each ofthem.