Godot is more polished and excels for 2D and 3D is quickly evolving. Godot also has a great community. Xenko is better for high end graphics and large complex scenes - especially if pushing the edge in VR etc. Since going open source its evolving slowly but steadily. While It is missing some features compared to Unity and Godot it has an incredibly capable foundation and its very easy to build on. The Community is very small but active and it has a lot of promise.