Hey, I hope that you are well! I’ve used both Godot and Defold so hopefully I can answer some of your questions.
In my opinion, I find Defold easier. The flow of game objects in collections, in my mind, is a bit more straightforward than Godot’s node system. This part though comes down to personal preference.
Defold is great because it allows you to develop for different platforms. I have been able to create web games, and I am currently working on a mobile game that will also be released to PC. The mobile development is fairly simple, there are a lot of great resources to get you started.
I don’t think lua is very complex. It is fairly straight forward, but if you run into any trouble, there is always great documentation you can take a look at. One deciding factor for me when choosing between Godot and Defold was that Godot used gdscript. This scripting language is limited to the Godot engine and has no use anywhere outside of it. My thinking was, ‘might as well learn something that I can take with me and use somewhere besides Defold’.
Overall I have found Defold to be the better of the two, I hope that some of this information can help you come to a decision
Have a good one!