Here is how to export FBX models to Unity with perfect transform rotation values if you're suing Blender. Works perfectly with rigged meshes too. More details is in the comments. : r/gamedev
Exporting From UE4 to Blender or Mirroring Animations in UE4 - Character & Animation - Epic Developer Community Forums
How to Export a fbx-file in Blender with reduced keyframes | 3DHaupt
Animation not exporting correctly - Animation and Rigging - Blender Artists Community
3D model export and setup tips using popular 3D tools – Sansar | Help - Support, Community Forums, and Knowledge Base
FBX Export from Blender
FBX Export from Blender
HowTo/Export Blender FBX Animation - TrainzOnline
Blender Export Animations to UE4 and Unity - YouTube
Export cloth Simulation/Animation to .fbx file - Animation and Rigging - Blender Artists Community
Enfusion Blender Tools: Import/Export Animation - Bohemia Interactive Community