Shiina Ringo

Lol none of these singers have a discography as good as ayu's except for Utada Hikaru.
And then Eiko Shimamiya comes close. Half of these people haven't even put out an album better than Duty, MY STORY, I am..., etc tbh.

Depth in music is also important to me and ayu and hikki have that down with astounding quality. Even if lately ayu doesn't have as many gems, overall, she's still up there. But even without the depth, their music is still better.
I look forward to Hikki's new release since she's the only other artist to hook me as much as ayu.

For me it's Ayu but I choose Koda Kumi and Namie Amuro. Both of them are awesome as well. I love the music and theire stlye.

I know pretty much all Ayumi & Utada's songs. And I've been listening to Shiina for literally a week and I'm only 4 albums in and I already love her more. That says a lot hahahaha. I'm pretty shocked tbh. She's beyond talented and original.

I don't really view artists as better or worse exactly. I think it is all relative to how you personally feel about an artist.
Of this list there are artists on here that perhaps have a stronger vocal or is more skilled at dancing or completely creates all aspects of their music. But I have a stronger connection with Ayu regardless, so I just voted for other people that I like.
Most notably Aikawa Nanase. Her popularity is way down these days but I feel like she is one of the most consistent female artists active today. She is still releasing quality work 20 years later.