The greatest champs globally to counter Renata Glasc include Kalista, Lucian, and Vayne. These are all good at countering Renata Glasc with high win rates over 58%. Even if these Renata Glasc counter picks are not picked in your lane, it's not a good idea to play them into one of these matchups. They will likely win against Renata Glasc.
Yet, if the opposite team picks either Gwen or Ryze, you should strongly think about taking them, as they easily crushes these champs with win rates over 56% against each ofthem.