Godot is OK, I really don't like GDScript and as far as I know its 3D support is lackluster. I check the Godot subreddits now and then to look at projects and nothing is really impressive.
In my opinion, if "open source" is a necessity, then Godot currently seems like the leader in terms of community support and maintennance, otherwise I'd suggest going with Unity, even for 2D, and waiting until Godot's featureset matures a bit more.
Why the downvotes? Godot is a perfectly fine engine to start out with. There's a couple other options like: https://xenko.com/ and http://www.monogame.net/ *monogame is actually a Framework so you won't get an editor window or many of the bells and whistles you'd come to expect, but it's quite robust and some popular games have been built with it.
My experience in game development pretty much amount to an incomplete multiplayer tetris game.