The greatest champions out of lane to counter Ryze include Aphelios, Lucian, and Caitlyn. These are all good at countering Ryze with high win rates over 57%. Even if these Ryze counter picks are not taken in the same position as you, it's not a good idea to take him into any of these matchups. They will likely beat Ryze.
Conversely, if the other team choses either Braum or Kog'Maw, Ryze mains should seriously think about choosing him, as he easily dominates these champions with win rates over 53% against each ofthem.