Strongest versions of each.
I am not sure but i think this is stomp in favor of Uriel.
True true, but universal or stuff like that is not enough. An universal blast may vaporize Uriel, however he will be ok, as I say, no matter how powerful is seiya he won't be able to kill Uriel due to eternal atoms; Uriel must be killed in physical, spiritual and astral planes, and it must be done in each plane to atomic elimination. Also probably seiya attacks won't really hurt him due to dispel.
This is a total stomp in favor of Seiya, He was capable of resisting Apollo (Who was easily a universals reality warper, erasing and recreating a universe with a hand wave)
Regardless, Seiya wins. A LOT faster, and he can attack the Eternal Atoms just fine.