HumanGen has a problem with its Rigify rig. The arms don't work properly.
To work around this issue I do the following:
- Use the HumanGen face mesh because it has better textures
- Use the MB-Lab body because it has a better rig and better proxy system
- Generate the humangen face rig
- Delete the humangen body bones leaving the neck and above
- Add an MB-Lab model and finalize it
- Add an MB-Lab Rigify using the Rigify-for-MB-Lab model. Note you'll need to use Blender 3.6 to do that since the add-on doesn't support bone collections yet.
- Add a copy transform constraint on the human gen neck and head bones and get them to follow the MB-Lab Rigify neck and head bones
- Disable the copy tranforms on the bones above and add the face it rig. This is needed in order for the binding to work properly.
- Make sure the faceit rig is the top of the modifier stack
- Make sure to remove the single pixel in lip_lower_vg_b from the lip and jaw vertex groups because that single pixel is used to move the lower teeth.
- Re-enable the copy transforms and everything should work correctly
- You can then add a set of clothes using MB-Lab's tools