I haven't tried Godot but I've seen some videos + your opinion on it and it looks great. I've been using Unity since I started, a bit more than 2 years ago and I never thought to switch to another engine. Maybe because it took me some months to understand it in depth. I had knowledge in C# before finding out about Unity and it was just great for me because it used putted in use all my previous knowledge. Do you suggest me to give it a try and maybe switch over or I should stick with Unity? I mean, is it easy to start using another engine after you get used to one?
An about the fee, I think that Godot is fairly new and it is looking for more users and it will have a fee later on... Just my personal opinion.