I used to be a big Ayu fan, the 100 Ayu songs I have is proof of that.
Nowadays I've starting getting into L'arc-en-ciel and Glay as well Korean popmusic.
But my favourites were (and still are) 'Evolution', 'Surrel', 'Free and Easy' and 'Monochrome'.
I haven't listened to much of her new stuff, yet I really like 'Moments' as well.
As for her singing skill, she's alot better more than what she was. I heard a live version of 'Unite' once and man was she out of tune.
But I was still a fan, my moblie ringtone was a Ayu song 'Audience' I also had 'Depend on you' and 'Boys and Girls' as a ringtone too. Even through it's has long been replaced with Eden, I've still got some of them on my phone. ^_^