Lumberyard have spent a lot of effort updating the engine over the past year. At GDC one of the devs told me about half of the code in the engine is from Amazon, while the other half is the Cryengine they used as a jump start.
They have a visual scripting language currently, but that is in the process of being improved/replaced. When we asked them for a ETA, they responded "when it's ready", so they aren't rushing it, but it was far enough along that they were willing to show it off at their booth.
Lumberyard is designed to be completely free, and you only pay if you use the amazon web services, which it makes easy to integrate. The other unique perk of Lumberyard is it is integrated with Twitch if you want there to be interactivity between streamers and their chat.
Unity is better if you want to make 2D or 2.5D games, Unreal is a comparable option to Lumberyard if you want to make 3D games, with their blueprints being similar to the current implementation of visual scripting in Lumberyard.
Like LS said, you're going to have a hard time finding assets for your game, unless you make them, or find someone who does, or have low standards (in which case, Kenney, aka Asset Jesus, is all you need).