I am a bit puzzled by such a strong desire for A Best 3. It would seem like a rather pointless release for fans. Most fans don't even by CDs anymore and just stream or download her songs so everyone already has full access to all her past songs. A Best 3 would mostly just be a collectible release for fans that love physical copies or must have a complete collection of everything Ayu.
In the past A Best releases don't really include much, just a small handful of redone vocals on the original A Best and then A Best 2 had an extra song Part of me, a countdown live DVD, and music videos. So if A Best 3 is done, I would like there to be some substantial exclusive content on it to give more incentive for fans to buy it.
I would much prefer A Ballads 2. If it was done the way the original was, we would get a bunch of exclusive alternative versions of her ballads and maybe a new ballad like RAINBOW. It would just be a more valuable release in my eyes.