EN Paimon might be one of the worst voices in the game, but I like JP Kaeya a bit more than CN because he sounds a little more smug and playful.
Xiao is the most distinctly differing between voices.
CN is kinda soft but strong, best fitting for him.
JP is your anime edgelord, quiet mostly but also angry at the same time, it works well too.
KR is a very sexy man, and as pleasant as the voice is, it doesn't fit.
EN is awful, overly agressive sounding and it's very obviously a woman.