I have come up with this conclusion...

***<<<<SPOILER ALERT>>>>>***




The one who won was no other than KYO, but it's not that easy as only to say that kyo won.
When you see the battle between kyo and kyoshiro you clearly see that Kyoshiro falls to the ground, then when Yuya appears at the battle field shes met by Kyoshiros body.
Kyo won becuase he now mastered al the elements that Murasama tought him, and fighting for Yuya, Kyo aimed to inherit the title "The Strongest". When he now deafeted Kyoshiro, Kyo and Kyoshiro became one again (two became one) and so Kyos body disapeared. The diffrence between the now existing Kyo / Kyoshiro was that KYO was the dominating part as he had developed from a ruthless killing machine in to something more human.. And taken to considaration that Yuya promised to give back the medecin boxs to Kyoushiro earlier in the anime, yet she was the one carrying the medecin box and doing Kyoshiros job, because kyo wouldn't carry such a thing, he was there just to protect the one he loved. And The smile, the clothes and the voice of kyo clearly inidactes that it is Kyo not Kyoshiro existing.. Because we know to kinds of kyoshiro, the funny guy, and the serius guy, if it had been the funny guy (kyoshiro) wich everyone knows from the beginning of the anmie, he would have fooled around and carried the box and perhaps lived with Yuya, but thats not the case, everyone can see this.. And if it had been the serius guy (Kyoshiro) then he wouldn't have lived with Yuya but indeed with Sakuya, the woman HE loved... And remeber, Kyos will to live was actually stronger than kysohiro that was prepared to die for Migura. And that will deafeted Kyoshiro.. But as I said before, kyoshiro never disaperes he becomes one with Kyo, but Kyo is dominating the body and mind, perhaps more loving of Yuya then before..

Love conquers al!
KYO!!!!