[Not Fade Away]

^This.

And people keep bringing in things like who sings with more emotion and who has a voice that gets boring after a while, but I'm pretty sure the poll is supposed to be on vocal techniques and how well the quality of the voice is.

That being said, I can clearly notice deterioration in Ayu's voice, so sometimes it's extremely difficult to listen to her. I don't really connect with her voice so much as I connect with the things she is singing about. For me, I love Ayu more for her lyrics and messages rather than the quality of her voice.

Utada, however, has remained strong vocal-wise since the beginning of her career. And - actually - she's had vocal training earlier than 2004, I remember her talking about it in her blog posts waaaay back when. She's also had vocal lessons as recently as 2009/2010 because she mentioned she had to have them because of the problems her vocals suffered during promotions for 'This is the One'.

Also, Hikki's vocals are extremely dynamic if you listen to all of the tracks on her albums and not just her singles or go-to songs.

Overall, I would choose Hikki. I've heard her growth and maturity in her vocals over the years and I think she sounds smooth and strong when she sings.