In my opinion, KOF's Japanese voices aren't even that good. I blame Yuri and Hwa for the most part (Their voices are just too annoying and they hurt my ears). If only the majority of KOF seiyuu's don't overuse the Kansai dialect, I will approve of the Japanese voices.
To be honest, the only Japanese voices I like are BlazBlue's, Virtua Fighter's, Tekken's, and a few other Japanese game's original dubs because they are much better and don't overuse (or not use) the Kansai dialect at all.
KOF's Japanese voices (only those with Kansai dialects) suck in my opinion. The only voices that are good in KOF are Iori, Athena, Mai (As of XIII), Andy, Joe, Raiden (XII only), Chin (XII~onward), Tizoc, Gato, Yamazaki, and a few others whose seiyuus actually did not use a Kansai dialect.