She may be unique but she is nowhere near as good as the others. (Don't even get me started on her Gum notes)
Overall I never really cared about her design to much but The new one is nice. (Her Taiwanese design is the only one of the Taiwanese designs that I can somewhat stomach because it is only a little different from her original design.)
I think she means she likes Sonika's voice more than other Engloids, not voice quality.
Anyway, the current English one, although the Taiwanese isn't far off either. Her original...ugh.