Conditions: Both are alive (Scenario 2: Both are Edo without Regen.)
Knowledge: Manga
Battlefield: Great Naruto Bridge
Distance: 20 Meters
Restrictions: None
I guess some could go ahead and state that Asuma, however, in the end that is false. No matter how you look at it, Asuma cannot get past Zabuza's Kirigakure no Jutsu so Zabuza should be the victor here.