The Naruto Verse will win.
Why?
Shinobi are trained for the kill, they are weapons nothing more. We all know this. Sound and Sand vs Leaf a lot of kills really a freaking lot of them.
Benders are trained to defend not really to kill, firebenders do this because they are evil, the finale of season 1 it was a war where almost no one died. The invasion, the firebenders surrunded.when your enemy is down on power the shinobi just kills them.
okay Naruto did not kill Pain Reason: he wants to complete his Sensei his dream. He tried to kill Kakazu only Kakashi finished it. Naruto did not kill haku he did not have the nerve for it. He did not wanted to kill gaara cause he felt his pain (Sasuke was trying to kill them both).
Katara she wanted to take revenge she failed. Aang needed to kill Ozia he just took away his bending skills. Zuko and Katara did not Kill Azula while she tried to kill them.
We all know wich side gots the brains. the Shinobi. Shikamaru, Kakishi, Sasuke you name them are all very smart and they discover the movements of the benders really fast.
Benders their smart Guy is Sokka..... and he is almost as smart as Kiba.
only the Avatar can use all elements. Good Shinobi can use 3.
Shinobi can uses clones, With the likes of Naruto they will have a never ending army.
and shadow clones don't bleed so they can't get struck by bloodbending.
Chakra this is the flaw of the Shinobi, some of them don't have so much and when chakra runs out you can die. Bending is your own Stamina so advantage for them.
Speed. Shinobi, their running is just as fast as an Airbender when they are just genin.
Summons, Big Snakes, Slugs, Frogs, Spiders, Demon Doors and more of that shit. more milatary power.
Ilusions an other win for the Shinobi.
I think avatar is a cool serie, but they cannot beat the Naruto verse (this is the same idea as DBZ vs Naruto) Shinobi have to much advantages and i did not even write them all.
(i know my english is not that good so deal with it)