I'm going to give credit to where credit is due and vote "Other".

There are other Japanese female singers who have better trained and controlled vocals than these "well known" ladies. I am a devoted fan to some of the artists listed but I'm going to keep it real and put 'fandom' aside. There are MUCH better female vocalists in Japan.
(Misia
"phenomenal vocals", ayaka, Thelma Aoyama, Crystal Kay, Beni, Superfly, Angela Aki, Miho Fukuhara
"superb voice range", etc...)