After 2 years of development, Godot 3.6 is finally out and it comes fully packed with features and quality of life improvements! This includes 2D physics interpolation and hierarchical culling, and 3D mesh merging, level of detail, tighter shadow culling, ORM materials, and more.
As well as providing support for existing 3.x games, Godot 3 has developed into a mature and stable codebase, which is well suited to development for low-end hardware. The development emphasis is on backward compatibility. Any new features are optional and we strive to not break or alter existing functionality.
To me, Godot is the only game engine I would ever consider using. Unity is bad because you never know what shitty stuff they'll do next. Unreal probably doesn't work on Linux and unreal script sounds like a terrible idea. If I had to figure out all those extremely difficult math problems like angular velocities, quaternion math, rotation matrices and shit in an obscure programming language, I would stop to rethink my life choices. It's already hard enough doing this in more widely used established languages even with decades of stackoverflow posts available.
Besides Godot, you can always make your own. Use a graphics library like orge or Irrlicht, a physics engine (reactphysics3d for example), something for sound like openAL and once you get them all glued together, you have a game engine.
While most of the development focus today is on 4.x releases, enthusiasts have been busy improving the 3.x branch: fixing bugs, optimizing and increasing reliability, providing quality of life improvements, and adding new features.