Best openworld game to mod?

[Jakers123]

Hi everyone, I love creating 3d models of cities and buildings, sadly I only know how to make them in Google sketchup, but I more or less know how to convert them, so that's not the problem, anyway, since I love creating cities, what game or engine would be the easiest for me to put them in, to ,,free roam" and to perhaps have AI walking/driving around,etc...?

I would love to create models for GTA SA, since there's a few mods with entire different russian cities made, but modding SA is a little hard to learn.

Few years ago I created a small ,,Greek island town" in Cryengine and Cryengine is currently my favorite choice, but I have some problems with saving texture data (every time I open the map, the info I previously saved for the materials (like transparency, whether is it a metal, water type,etc.) disappears)

So if anyone has any ideas, I am listening.

[VPaulus]

Maybe ArmA 3...

[wings7]

Fallout New Vegas, Fallout 4...

[Kuokkanen]

ORIGINAL: VPaulus

Maybe ArmA 3...

= Armed Assault 3

[wodin]

ARMA 3 I concur.