People are obsessed with Don to an annoying degree, but I can't deny that I love chuuni characters. Anyway, her personal E.G.O. had the least impact of all I've seen, and to use your conparison, even Gareth's okay NP animation had more impact because of its ending.
Her VA did a few chuuni characters before Don, like Konosuba's Megumi, she seems like a good fit honestly, the voice is surprisingly not very high-pitched, which I prefer. For now, both Yi Sang and Don don't seem like bad characters.
Why do you dislike her so much though?