Catchiest Ayu songs?

[noisy_harmony]

As a k-pop fan I'll try to get into that problem xD
NEXT LEVEL album
LOVEppears album
(miss)understood album
all stample songs - evolution, Boys & Girls, UNITE!, AUDIENCE, Trauma etc. (not all of those are in the typical k-pop tune, not in the temporary tune at least, but they're catchy after all!)
upbeat songs from RAINBOW like WE WISH, everywhere nowhere
Connected
Naturally
INSPIRE
STEP you
Ladies Night
until that Day...
cutesy songs! Beautiful Fighters, ANGEL'S SONG, HONEY

Some of them was already mentioned so they're the best options as you see
Of course k-pop is not only dance/electro/up-beat as everybody would think. I think you can try with some ballads too.
They all are not my favorites, I just type the most "safe" songs:
Days
HEAVEN
RAINBOW
Dearest
CAROLS
No way to say
Moments
walking proud
rainy day
JEWEL
Together When...
Who...