You're mentally ill. The division beat the G and S Brothers, not Darui alone. Zabuza can hide from Storm Release because he has his mist. Idc if he learned black lightning
Actually...Ginkaku-sama and Kinkaku-sama laid waste to the Division....they were beaten by a conveniently timed Darui Plot-Shield...How many times does your MOST USED PHRASE get replaced SECONDS before game over.....it doesn't.
OT: I'd still give it about a 50/50, but maybe with an edge on Zabuza.
Zabuza
1. Hidden Mist
2. Silent Killing
3. Water Dragon
4. Water Vortex
5. Water Prison
6. Water Clone
7. Masterful Kenjutsu
8. Blood Replenishes sword
9. High Pain tolerance
10. Greater Brute Strength
Darui
1. Ranton
2. Black Lightning
3. Water Wall (which does create a barrier that can encircle you as I recall)
4. Descent Kenjutsu
5. Lightning Application to Kenjutsu
6. Quick Reaction Time
7. Good Agility
8. Quick Learner
Now....for the most part...Hidden Mist is Darui's bane....his greatest moves (Ranton and Black Lightning) are rendered nearly useless in the face of Zabuza's mist. As a result...they can mostly be used to defensively ward off Zabuza's charge with a last minute attack. Additionally...Zabuza can direct his attacks at Darui because he can apply his silent killing skills with his jutsu to aim in the mist.
In response, Darui has the ability to react quickly such as what he did when he randomly dropped out of his defeat against the Gold and Silver Brothers.....he instantly slashed one of the brothers and caused the other to be sealed.....damn good reaction time keeps Darui from harm for a good bit of time. Additionally would be his quick learning feats.
With limited time, Darui could analyze how to use the Sage Tools, and applied them with perfect action. This would be key in allowing him to figure out Zabuza's battle plan if his agility helps him survive several silent killing strikes. Similar to Kakashi, Darui would likely be able to figure out Zabuza's attack strategy if he is given enough time. If given this time...suddenly Darui is at the advantage...because 1) He knows the patterns and can thus attack, not defend. 2) Has a higher caliber offense (Ranton...Kuroh Raiton). 3) Has the agility to perform counter attacks with a predicted pattern.
Still, Zabuza's other bonus would be to use Water Clones to mess with this timing leading to a false game pattern...which could render Darui unaware of his true attack strategy. Additionally, Zabuza also has the edge in sword combat so if he closes the gap on Darui, he has the advantage of physical dominance as well as Kenjutsu skills. Furthermore, Darui could once again be played with....While his Raition applied Butcher Blade could cut the Executioner blade...there are two risks.
1) Time: Sounds retarded, but remember Zabuza is stronger, and with enough force could cause Darui to slowly cut through the Executioner blade. The minute this happens...a water prison can be applied...or as another option, Zabuza can simply use sheer physical dominance to suddenly have Darui in a choke hold...or one hand the Executioner's blade while using a Kunai to end it.
2) Regeneration: If, persay, the blade was quickly cut...he would most likely not know of its regenerative power by absorbing Iron through blood. As other than seemingly the Hidden Mist Swordsman Enthusiest Suigetsu...no one else seemed fully aware of their full potential...not even Kakashi until it was being used in front of him for the second time. As such, Zabuza could retreat into his mist. Analytical, Darui would naturally re-calculate Zabuza's required closing distance, and could thus be caught unaware were Zabuza to replenish his sword with his own blood.
Conclusion
To me this seems like a game of time. The longer it takes Zabuza to kill Darui...or better said the more times he fails to kill Darui...the better chance Darui has to get a grasp of the situation. Darui may not have the sharingan for move prediction; however, he's still an extremely talented shinobi. If given enough time to see through the Hidden Mist pattern, Darui will have the advantage in fire power; however, the initial advantage goes to Zabuza...and if it comes to prolonged CQB, Zabuza takes it with Superior Kenjutsu IMO.
So like I have said....a race against time...but considering Zabuza's abilies in cloning as well as Silent Killing...he has an edge. At the lowest he wins 5/10....at best I'd give him 7/10. Darui isn't to be underestimated as well.