If you let an IDOLiSH7 unit cover another unit's original song, what would it be?

If you let an IDOLiSH7 unit cover another unit's original song, what would it be?

Here are a few examples:

IDOLiSH7 covers Poisonous Gangster by ZOOL

ZOOL covers SECRET NIGHT by TRIGGER

TRIGGER covers SILVER SKY by Re:vale