Generally speaking, most teamwide calcs show that Shenhe performs better than Kazuha and Ganyu Support in one to two target situations. In AoE, Kazuha and Ganyu can both get quadratic scaling, which allows them to outperform Shenhe’s single target Icy Quills. This is actually good game balance and shows that Shenhe is roughly as valuable as Kazuha or Ganyu in the same slot as a support, with each unit excelling a bit over the others in a specific situation. It is also worth mentioning that Shenhe has high synergy with both Kazuha and Ganyu to amplify her Icy Quills further, or can replace them as a support so you can possibly use Kazuha or Ganyu on your second abyss team.