Actually, Seiya, Mars, and Ikki would be the first two to lose and die because even though Seiya is powerful and can even injure Hades and crack his Kamui, he's still below the strength of a God.
And why would you put that stupid spin-off character from Omega in here? Personally, Omega is crap.
Anyways, Zeus inevitably wins but with some high difficulty since Typhon, Hades, and Kronos are his opponents. Albeit Athena may be an opponent but she's no big of a threat in comparison to the other three Gods that are beyond over hax! Zeus may be featless but by power scaling, he's the strongest god in Saint Seiya.