I come from Architectural background and hoping to use UE4 for animation. I currently use Archicad and want to know which format i can ecxport to UE4.
You can import fbx and obj files into the ue4 
-> for animations you should use fbx
Thank you.
OBJ is very limited, so it’s best to use FBX
Just in case that you want to see in which cases the obj format is limited:
https://forums.unrealengine/showthread.php?6124-Unreal-Engine-4-2-Update-Preview
New: OBJ Mesh File Format Support
You can now import .obj files for static meshes!
The file format is very simple so keep in mind that it does not support the following features:
- Vertex color importing.
- Collision importing.
- Tangent and binormal importing.
- Transforms.
- The model will be rotated if not modeled with Z up because with OBJ importing we have no way of getting the source coordinate system.