The top picks out of lane to counter Зилеан include Калиста, Тристана, and Сивир. These champions are all good at countering Зилеан with win rates over 57%. Even if these Зилеан counter picks are not used opposite your position, it's not smart to take him into these matchups. They will usually beat Зилеан.
Conversely, if the other team brings either Квинн or Скарнер, you should strongly consider selecting him, as he easily wins against these champions with win rates over 55% against both ofthem.