Unity and Unreal = Huge engine that can make life like multi-million dollar games. Can be overwhelming for small teams
Godot = Awesome engine where almost anyone can make a game quickly. Release a game in a week or you can work with a team for over a year with a polished game. Godot is the killer Indie Game Engine due to how easy it is to make a game but you can really get something that scales but it isn't as capable as Unity or Unreal.
Godot vs Luxe (Haven't programmed in Luxe yet) - Godot you really using a lot of menus to make your game, though you can now in Godot 3.0 do everything (mostly) code based now (Great thing in my opinion). Luxe seems to try and make it more code based with the ability to use menus and a API that will allow you to use almost any language (Though I think languages similar to Python with a ton of libraries might not be well suite for porting. I really think Racket would make a killer game scripting language if people will get over brackets.