Are you planning on releasing the UE4 project to the public? Or only builds? I'd love to play around with it in the editor if possible!
Please make the second floor..!! and if you've done it please tell me where can I find it...??!
In the last few years Fusion 360 became very popular among 3D artists.
Its capabilities of dealing with complex booleans and edge beveling of difficult forms made it the tool of choice for more and more hard surface artists.
A downside has always been the mesh triangulation if you want to export your CAD model for usage in games.
This is what a common export looks like.
You have got full control over the polycount in the Moi 3D exporter.
All your bodies from Fusion 360 are available as perfect editable n-gon meshes.
You can unwrap and edit the asset and push it to Substance Painter, Unreal Engine 4, Unity 3D, etc.