It would be a matter of preference as to which texture you prefer. Using
Minimal's Tools (extract where you like it, you'll use these tools frequently) and
Scanti's Texture Tool (you can have multiple instances extracted where ever) and an image editor (GIMP with dds plugin and normal map plugin if you want to view and edit), you can:
1. Unpack "sr3_city_awld.str2_pc" file from each mod to separate folders using "ThomasJepp.SaintsRow.ExtractPackfileGUI.exe", proper labelling for later might be important. "Admixon" and "Billboard" could be possible naming for top level folder, including one for finalizing your picks of the mix. I'll use those names for the rest of this tutorial.
A. So, Unpack (step 1 above) packfile from Admixon's textures to a folder "Admixon".
B. And, Extract (7zip/WinRAR) Scanti's Texture Tools to the folder above, "Admixon".
C. And, Unpack (step 1 above) packfile from gameqube's textures to a folder "Billboard".
D. And, Extract (7zip/WinRAR) Scanti's Texture Tools to the folder above, "Billboard".
The result of unpacking will be two files from unpacked "sr3_city_awld.str2_pc"----> "sr3_city_awld.gpeg_pc" & "sr3_city_awld.cpeg_pc".
Each step from here should be done separately for each mod, using 7zip or winrar, extract Scanti's Texture Tools once into your "Admixon" folder, once into your "Billboards" folder. Here's a visual of created folders for working and subfolders with dashes showing second level subfolders:
"Admixon">
-------------->"sr3_city_awld.str2_pc">"sr3_city_awld.gpeg_pc" & "sr3_city_awld.cpeg_pc"
-------------->"SR3TextureUtilities6">"SR3UnpackTextures.exe" & "SR3RepackTextures.exe"
"Billboard">
-------------->"sr3_city_awld.str2_pc">"sr3_city_awld.gpeg_pc" & "sr3_city_awld.cpeg_pc"
-------------->"SR3TextureUtilities6">"SR3UnpackTextures.exe" & "SR3RepackTextures.exe"
2. Create another folder for finalizing your prefered mix of textures, say "My Mixed City Textures" for sake of descriptive. Create another folder called "sr3_city_awld.str2_pc" within "My Mixed City Textures"; this will be where you will repack/build the actual "sr3_city_awld.str2_pc" file. Visual:
"My Mixed City Textures">
-------------->"sr3_city_awld.str2_pc" (this folder should be empty)
-------------->"SR3TextureUtilities6" >"SR3UnpackTextures.exe" & "SR3RepackTextures.exe"
2. Once the folder structures above are created, and you have unpacked "sr3_city_awld.str2_pc" to corresponding folders in steps 1&2, copy the "sr3_city_awld.gpeg_pc" & "sr3_city_awld.cpeg_pc" into your "SR3TextureUtilities6" folder, where you should have "SR3UnpackTextures.exe" & "SR3RepackTextures.exe" files and a "readme".
Example visual of first folder after copying:
"Admixon">
-------------->"sr3_city_awld.str2_pc">"sr3_city_awld.gpeg_pc" & "sr3_city_awld.cpeg_pc"
-------------->"SR3TextureUtilities6">"SR3UnpackTextures.exe" & "SR3RepackTextures.exe">"sr3_city_awld.gpeg_pc" & "sr3_city_awld.cpeg_pc"
3. Now drag and drop the "sr3_city_awld.cpeg_pc" onto the "SR3UnpackTextures.exe" in "SR3TextureUtilities6" and a DOS window will show quick work of extracting the actual textures into the "SR3TextureUtilities6" folder. Now you will have a bunch of ".DDS" files.
4. Repeat step 3 for gameqube's "Billboard", using the corresponding folder.
5. View and compare which you'd prefer from both "original" unpacked mods, copying these files to "My Mixed City Textures">"SR3TextureUtilities6".
6. Once you have your prefered mix and match completed in "My Mixed City Textures">"SR3TextureUtilities6" and you are sure NO TEXTURE IS MISSING, ie, file count should match original file count, drag and drop the "sr3_city_awld.cpeg_pc" in "My Mixed City Textures">"SR3TextureUtilities6" onto "SR3RepackTextures.exe". The result will be newly dated and packed "sr3_city_awld.gpeg_pc" & "sr3_city_awld.cpeg_pc" files. Copy these to
"My Mixed City Textures">"sr3_city_awld.str2_pc".
7. Using "ThomasJepp.SaintsRow.BuildPackfileGUI.exe" from Minimal's Tools, select game (SR4), point source to "My Mixed City Textures">"sr3_city_awld.str2_pc". Click "build", point to SR4 game folder and name the file "sr3_city_awld.str2_pc" without quotes.
8. Use "ThomasJepp.SaintsRow.Stream2Update.exe" from Minimal's Tools to rebuild the .asm files (or game will crash).
Using the three working folders method ensures that you can go back later without unpacking again and again. Good luck!