There has been some talk about modeling workflows for Bannerlord. The PBR workflow is not the same as what some around here may be used to, and I've gone through a few different paths myself, so maybe I can share about things that have worked for me and might work for you.
This is not a tutorial on how to use any of these programs. There are many of those out there already. This is just an overview of what kinds of programs are used for this kind of thing, and a starting point for you to go out and research them yourself.
PBR Texturing:
This is a new way of texturing that makes use of fancy new rendering engines to make materials really shine in-game. They use realistic values of color (now called "albedo"), metalness (how metallic something is) and roughness (how smooth something is). metalness and roughness are also replaced with "specular" and "smoothness" in some workflows. They do the same thing, but somewhat differently.
For PBR texturing, the materials rely heavily on normal maps, more so than previous workflows. So, you will need to create both a low poly model as well as a high poly model. In the past, we could generate normal maps by hand, and this is possible, but the results are not likely to be as good.
Here are some of the programs that you can use to figure out your own workflow. I've listed some free versions, as well as paid versions. This is not an exhaustive list, simply a list of programs that I have personally used and my own personal opinions about them. I would love to hear more (and differing) opinions in the comments!
Low Poly Modeling:
Free options: Blender, Wings3D, student versions of more expensive software
$$$ Options: 3ds Max, Maya, Modo
My opinion: There is a trap here. Wings3D is ridiculously easy to use and intuitive compared to these other options, but at some point you will hit a wall where you can't do everything you want and you'll have to start learning one of these other programs, where you will just wish that it was like Wings. This is where I was, and I HATE modeling in anything other than Wings, but I have to now to get the better options that are available in those programs. So you might want to just SKIP Wings and go straight to one of the other programs. Blender is free, and can do most of the stuff that the more expensive ones can do, so you can absolutely get away with using it. Many professional products have used Blender. Aside from that, 3ds Max and Maya have student versions for noncommercial work which will give you a good chance to try out the products. They take a real time investment to get to a point where you can be productive in them, though.
High poly modeling:
Free option: Sculptris, Blender.
$$$ Option: Zbrush, Mudbox
My opinion: I won Zbrush as part of a prize package in a 3d modeling contest, and although I do prefer it to sculptris, you can definitely get pretty far just using the free option, especially if you look around online and find some free brushes and such. If I hadn't won it, I would not have paid the very expensive price for it, and would have made do with sculptris for as long as possible. Don't get me wrong. Zbrush can do a LOT more than Sculptris can, but for hobby work, it gets the job done. I haven't tried sculpting in Blender, but I believe it is usable as well Just expect to spend much more time getting it done and your computer will probably start running slower much sooner.
Extra note: For models with hard edges, you'd probably be fine making your high poly model in Wings or Blender and skip the sculpting step altogether. A lot can be done by just adding more edgeloops and geometry. Sculpting is better for models like armor, clothing, bodies, etc.
Baking:
In order to generate a normal map, you will need to bake your high-poly model down to your low-poly model. This is used to trick rendering engines into thinking that your low poly model is more detailed than it actually is (kind of).
Free option: Xnormal, $$ Option: Bake inside Substance Painter.
There are a lot of baking options out there (3D coat, Knald, Max, Maya, Modo, etc.) but Xnormal is fine and will do the job well. I use Substance Painter, because I already own it, but I used Xnormal a lot before and still got good results.
Texturing:
Free option: GIMP + online material libraries.
$$ Options: Photoshop + Quixel, Substance Painter/Designer
My opinion: I use both Quixel, and Substance for my texturing. Substance Painter is my preferred tool, but I often go back to the quixel suite's superior normal map tools often. Substance Painter's ease of use is much better than Quixel's, in my view, and Quixel also requires a photoshop license to run. Both Quixel and Substance allow you to paint directly onto your model, which is a great way to texture!
I don't have Substance Designer yet, so you can definitely get far just using Substance Painter.
This is probably the area where staying free is hardest. PBR texturing relies on precise values for specific materials, so it can be hard to make your own. Luckily, there are a lot of free material libraries online where you can download woods, leathers, metals, bricks, etc. With a bit of work, you can cut and paste these into your layers in Gimp or Photoshop so it is definitely doable whilst being most assuredly slower and more labor intensive than using the paid versions.
To my knowledge there is no free program that is great for PBR texturing at the moment. (Please let me know if there is one I'm missing!)
Allegorithmic does allow for a 1 year student license to use their whole suite, though! So definitely give that a shot if you want to check it out.
If your model is all one material, then this isn't a problem, because there are a ton of options for downloading single seamless materials that you can apply to your whole model, but it does get more difficult when you are doing a model that has many different materials in it (like armor or something).
If you've got some money to spend, this is where you'll get the most bang for your buck.
I hope that this has helped somewhat for those who are not familiar with PBR workflows.
Links
https://www.allegorithmic.com/products/substance-painter
https://www.gimp.org/
http://www.wings3d.com/
https://www.blender.org/
https://quixel.se/suite2/
https://freepbr.com/
http://www.xnormal.net/
This is not a tutorial on how to use any of these programs. There are many of those out there already. This is just an overview of what kinds of programs are used for this kind of thing, and a starting point for you to go out and research them yourself.
PBR Texturing:
This is a new way of texturing that makes use of fancy new rendering engines to make materials really shine in-game. They use realistic values of color (now called "albedo"), metalness (how metallic something is) and roughness (how smooth something is). metalness and roughness are also replaced with "specular" and "smoothness" in some workflows. They do the same thing, but somewhat differently.
For PBR texturing, the materials rely heavily on normal maps, more so than previous workflows. So, you will need to create both a low poly model as well as a high poly model. In the past, we could generate normal maps by hand, and this is possible, but the results are not likely to be as good.
Here are some of the programs that you can use to figure out your own workflow. I've listed some free versions, as well as paid versions. This is not an exhaustive list, simply a list of programs that I have personally used and my own personal opinions about them. I would love to hear more (and differing) opinions in the comments!
Low Poly Modeling:
Free options: Blender, Wings3D, student versions of more expensive software
$$$ Options: 3ds Max, Maya, Modo
My opinion: There is a trap here. Wings3D is ridiculously easy to use and intuitive compared to these other options, but at some point you will hit a wall where you can't do everything you want and you'll have to start learning one of these other programs, where you will just wish that it was like Wings. This is where I was, and I HATE modeling in anything other than Wings, but I have to now to get the better options that are available in those programs. So you might want to just SKIP Wings and go straight to one of the other programs. Blender is free, and can do most of the stuff that the more expensive ones can do, so you can absolutely get away with using it. Many professional products have used Blender. Aside from that, 3ds Max and Maya have student versions for noncommercial work which will give you a good chance to try out the products. They take a real time investment to get to a point where you can be productive in them, though.
High poly modeling:
Free option: Sculptris, Blender.
$$$ Option: Zbrush, Mudbox
My opinion: I won Zbrush as part of a prize package in a 3d modeling contest, and although I do prefer it to sculptris, you can definitely get pretty far just using the free option, especially if you look around online and find some free brushes and such. If I hadn't won it, I would not have paid the very expensive price for it, and would have made do with sculptris for as long as possible. Don't get me wrong. Zbrush can do a LOT more than Sculptris can, but for hobby work, it gets the job done. I haven't tried sculpting in Blender, but I believe it is usable as well Just expect to spend much more time getting it done and your computer will probably start running slower much sooner.
Extra note: For models with hard edges, you'd probably be fine making your high poly model in Wings or Blender and skip the sculpting step altogether. A lot can be done by just adding more edgeloops and geometry. Sculpting is better for models like armor, clothing, bodies, etc.
Baking:
In order to generate a normal map, you will need to bake your high-poly model down to your low-poly model. This is used to trick rendering engines into thinking that your low poly model is more detailed than it actually is (kind of).
Free option: Xnormal, $$ Option: Bake inside Substance Painter.
There are a lot of baking options out there (3D coat, Knald, Max, Maya, Modo, etc.) but Xnormal is fine and will do the job well. I use Substance Painter, because I already own it, but I used Xnormal a lot before and still got good results.
Texturing:
Free option: GIMP + online material libraries.
$$ Options: Photoshop + Quixel, Substance Painter/Designer
My opinion: I use both Quixel, and Substance for my texturing. Substance Painter is my preferred tool, but I often go back to the quixel suite's superior normal map tools often. Substance Painter's ease of use is much better than Quixel's, in my view, and Quixel also requires a photoshop license to run. Both Quixel and Substance allow you to paint directly onto your model, which is a great way to texture!
I don't have Substance Designer yet, so you can definitely get far just using Substance Painter.
This is probably the area where staying free is hardest. PBR texturing relies on precise values for specific materials, so it can be hard to make your own. Luckily, there are a lot of free material libraries online where you can download woods, leathers, metals, bricks, etc. With a bit of work, you can cut and paste these into your layers in Gimp or Photoshop so it is definitely doable whilst being most assuredly slower and more labor intensive than using the paid versions.
To my knowledge there is no free program that is great for PBR texturing at the moment. (Please let me know if there is one I'm missing!)
Allegorithmic does allow for a 1 year student license to use their whole suite, though! So definitely give that a shot if you want to check it out.
If your model is all one material, then this isn't a problem, because there are a ton of options for downloading single seamless materials that you can apply to your whole model, but it does get more difficult when you are doing a model that has many different materials in it (like armor or something).
If you've got some money to spend, this is where you'll get the most bang for your buck.
I hope that this has helped somewhat for those who are not familiar with PBR workflows.
Links
https://www.allegorithmic.com/products/substance-painter
https://www.gimp.org/
http://www.wings3d.com/
https://www.blender.org/
https://quixel.se/suite2/
https://freepbr.com/
http://www.xnormal.net/