f(x) has lots of less known awesome songs like beautiful stranger, mr. boogie, ending page, airplane, dracula, beautiful goodbye, sorry, milk, etc (of course NU ABO, Pinocchio, Electric Shock rule
)
I also love:
SISTAR - Holiday, Loving You, No Mercy, Crying, 나혼자 (don't remember the English title)
Hyorin(girl from SISTAR) - One Way Love, Stalker, Lonely
SECRET - LALALA (랄랄라), My boy, UR Fired (I love this song), Madonna
SNSD - Whole new world of music (meaning awesome amount of gorgous songs)