HELP ME CHOOSE A VOCALOID SONG TO COVER !!!!

heyhey everyone on here !!!!!!!! i just impulsively bought megurine luka v2 !!!!!! and i cant decide what song i want to make her sing first !!!!!!!! i also have miku v4x so i could make a duet or one with her, but most of my fav songs use miku ^^ I LOVE LUKAS VOICE AAAAAA im so excited to get her !!!!! if u guys have any suggestions on what song i should use pls give me !!! i will set up a youtube channel to post it on and give the link !!!!!!!!!!