Kratos from God of War is the natural winner here.

And ofcourse, who could forget, The Vengeful Spartan

Ofcourse God of War is also played live by orchestras

This is the closest I'm going to get to getting involved in this argument:

Kratos' powers need to be clearly defined for any "match" that he's in, and it needs to be done in such a way that is concrete and definitive. Do the urns canonically exist, in terms of narrative? Yes, you can obtain them, but you can also obtain a cow costume and two plastic milk jugs to swing into enemies, and I don't think we would reasonably give him those either.

When he fights Sephiroth here, is he just a general? A flag-bearer of Ares? A god? A mortal who wields the sword of Olympus? From what point in time are we plucking Kratos from, here?

For that matter, from when are we plucking out Sephiroth?

Kratos.

Kratos redefined action games.
Kratos will rape Sephiroth over and over and over again any day. He will shave sephiroth's pretty boy hair, dislocate all of his bones, remove his teeth and make him read bed time stories all while single handedly killing the gods. Kratos will use Sephiroth as a battering ram and ram his head on a spiked wall repeatedly and decapitate him and eat his head for breakfast and use his body to distract all other FF characters.
:D

Kratos.

Even if he died, he would climb out of Hades, rewind time, and strange Sephiroth with a giant chain.

Kratos vs. Sephiroth?

KRATOS!!!!

Sephiroth:
-Killed a flower girl
-Got killed by some goth kid

Kratos:
-Has sex and leaves the girls
-Kills gods
-Escaped hatties
-Almost killed Zues
-Took a HUGE sword to the gut
-Rips enemies in half and rips out eyes (God of war 2, the giant cyclops fight)

Oh and Ryu doesn't stand a chance against a Kratos riding a cyclops. Ryu's suit will be ripped into shreds and he will be too busy covering his privates to worry about fighting Kratos who will, by that time, have ripped Ryu's anus and impaled him in a mast through his stomach and then through the lower jaw and next through the upper jaw ( like the Hydra in GoW1).
Other wise,
Chronos Rage ----> Medusa's Head ------> Smashed up -----> Grab by the head and stab him in the stomach, head and thighs ------> Repel magic attacks with golden fleece -------> and finally slice and dice and rip into half.
Ryu + Dante + Virgil + Kratos from ToS + Sephiroth + Dante (From dante's Inferno combined vs Kratos = Kratos WINS

Kratos could even beat Chuck Norris, I bet.

Dont speak ill of the dead 

But i think it will be an endless battle, lets say sephiroth lost then he is reborn and killed kratos who goes back in time and stop him and kill him, after that septhrioth is reborn once again .................etc...

You forgot a few things.

-He killed a 3 heaed hydra

-He destroyed the kraken

-He fucking climbed a titan and took pandoras box.

And Escaped hatties ? i assume you mean hades.. not only did he do that. He climbed out of the realm of the dead TWICE !