I recently decided the fastest way to work with Unreal is to throw it out and go with something else. It's like 10 fucking minutes to compile an empty project.
I like Godot primarily because of GDScript; you are not compiling anything so iteration time is greatly reduced. Unigine is also worth a mention. It has all the modern features you could want like double precision, global illumination etc but without the bloat and complexity. It's easy to use as much or as little of the engine as you need; in every project you write the main() function. Similar license options to Unity/Unreal.