Hi everyone
I made a lot of testing lately and here is a quick guide how to export your object and use it in Substance Painter.
1) Create your object in blender. Make sure it's UV mapped. Export it in .obj format with those preset:
2) In Substance make sure to select: "PBR - Metallic Roughness HQ (algorithmic)". Select your mesh and also be sure to use the OpenGL normal map format. The document resolution should be 2048
3) Once in substance be sure to bake everything. A lot of materials need the baked texture so I always bake everything before starting. If you reimport your mesh in substance (because you changed something in blender), don't forget to bake again.
Here is a few of my tests:
Tux (model wasn't changed)
A mine cart