This tier list is based on my personal experience playing each character, along with some considerations regarding their effectiveness in end-game content such as the Tower of Adversity and Whimpering Waves.
In this tier list, I assume that all 4-star characters are at S6, and all 5-star characters are at S0.

It’s important to note that some characters can perform significantly better when placed in specific teams that are built for them.

I’ll try to update this tier list with every patch, if any changes are necessary. After all, the rise and fall of each character’s performance is naturally influenced by updates, such as the release of new characters that can maximize another’s kit, the introduction of new Echo sets, or the appearance of 4-cost Echoes that can significantly impact their gameplay.