Princess Finis has some really formidable magical abilities but they take time to use. Nagumo’s speed means that he will be able to strike well before any of her songs start to make things dangerous. It’s why having super speed is so handy because at that point it is hard to stop you. Finis would need some kind of automatic barrier or something like that in order to stand a chance here. Nagumo wins.
Rin returns here but she won’t be able to defeat the more experienced song wielder. Princess Finis has shown a much greater proficiency with attack spells and her experience is worlds above Rin’s. You seriously cannot compare the two straight up at all. Their abilities are similar so naturally that means that the more powerful user would end up being the victor here. Princess Finis wins.