I'm not sure of my fav kuu ballads, since I like most of them for different reasons! Most people's favourite seem to be Yume No Uta or You but I don't listen to those two much, although re-listening to Yume No Uta I have realized how awesome it is again! I think it was because I hadn't listened to it for a long time...I really like Pearl Moon, Come Back, Kiseki, Hands, Moon Crying, Ai No Uta (Ashita E...And Alive because of their classical sound)....Believe because of it's gentle acoustic sound...And Aisho cause of it's cool rock sound and sexy lyrics.
No Way is beautiful as well.
But yeah, Come Back and Pearl Moon, and have always been two of my fav Kuu ballads. 0-ji mae no tsunderella is a def fav song of mine as well, or in Japanese, Ichiban no uta!
(I think..LOL)
I may have to put 1000 Words as my number 1 though, because it was the first Kuu ballad I ever heard and with Real Emotion got me into Kuu.