Scenario I: Snake Eyes. To me he just seemed like the more skilled swordsman. He moved better than those two vampire ninjas Blade fought in the second film. I like him for this scenario.
Scenario II: Blade. He has more weapons and knows how to use them. All Snake Eyes carried besides his blades is one pistol. Blade walks around with an arsenal that'd put Punisher to shame.
Scenario III: Blade. Both are skilled. Snake Eyes is probably more skilled. No, he is the more skilled martial artist. Blade incorporates street fighting moves into his own custom style. But Blade is factually superhuman. Snake Eyes is on the fence. I'd be more inclined to put him on the level of Nite Owl. He's not quite up there with Blade in the physical stats department. He'll last but Blade will eventually take it. Nomak is a far more dangerous opponent than Storm Shadow.
Scenario IV: Blade. Better stats and better weaponry. Snake Eyes is more skilled but not enough for it to make a difference.