I would say Piltover/Zaun because it's look like our modern world so i feel like the "technology" is the future. No matter which civilization will win, the technology will always win. Even if Piltover don't win the war, their techs will be used by others regions.
The only case where it's wouldn't happend would be if Bandle city took control of the world because they are creatures living in the forest. Obviously, they don't like technology because it's destroying nature.
Demacia is afraid of magic but, i don't think J4 would prevent Piltover from using techs. After all, Piltover isn't really an enemy of Demacia, and J4 is more open-minded and i think he would allow it. Ofc now he is a little bit against mages but i'm sure Shyvana will do something and cure his anger.
- technology isn't really magic, even if they use hextech, does Demacians see hextech as magic? I'm sure Piltovians could say "it's not magic, it's hextech" and Demacian people would not see it because they are so misinformed on magic. They know what magic is but they don't know what hextech is.
But Noxus would use them to develop their society.
Frejlord would be interested in some techs because they are living in a hard region (cold, savage and everything).
Azir or Xerath are power hungry and if Shurima took the world, they would use Piltover techs.
Ixtal with Qiyana, even if she don't like Piltovians, i'm sure she could find a way to use their techs for something. After all, when you discover comfort, you don't want to destroy it right? When she will learn about robots servants who can serve her at full energy, or when she will heard about social medias, i think she may change her mind on Piltovians and use their techs but turning them into slaves.
The shadow isles, i don't know because i don't really know the purpose of Mordekaiser. Does he want to control the world or kill the world? I think he would still use Piltover tech.
Bilgewater is full of pirates and i'm sure they are 100% interested in techs, especially when it's can give them power and money.
Ionia is peaceful like you said and Piltover won't have any problem to develop and expand their techs.