Ah, the engine question. First off, I think different engines are better suited for different needs and you should work with whatever you feel works best for you, your team, and your project. I'll go over my personal opinions of my top 4.
GODOT:
Godot is actually my personal favorite engine and the one I generally prefer to work in. I like that I am not beholden to corporate restrictions; it has a wide range of platform portability; and because it is 100% open source, I can easily modify it to suit the needs of whatever project I'm working on. I also think Godot is the best engine for professional 2D game dev. I think all of these advantages (plus it being 100% free) will help it take off in the 2D indie community.
UNREAL:
If you want to make a AAA (or AA) 3D game, it will probably be done in Unreal. (In fact, demand for Unreal skills are projected to go up by around 140% in the next year or so.) Recently, Unreal appears to be putting a LOT of effort into attracting indies and mid-sized studios (probably in a move to push the Epic store). In addition to increasingly great free asset giveaways, they have increased the amount you can earn before having to pay ANY engine royalties to $1million!
GDEVELOP:
For someone doesn’t know how to code and wants to learn game dev, this is a GREAT option! In fact, I’ve used this engine to teach game development to kids. It’s also great for throwing together quick prototypes and game jams. It’s similar to Construct (or to a lesser extent, GameMaker) but 100% free and open source.
UNITY:
I’ll talk about Unity’s pros in a moment, but you should know that while I think Unity’s ubiquity makes it necessary to know if you are a pro, I strongly dislike it.
I think (for now) Unity is a bit better for 3D game dev than Godot, and (for now) a bit easier to use than Unreal. BUT…I think Unreal is coming for them in the 3D space and Godot is coming for them in the 2D space. That combined with some infuriating recent decisions they’ve made solely to drive increased revenue for their IPO move…and, well…
For right now, Unity is solidly embedded in our industry due to years of great PR/marketing (and some hefty government grants). Many colleges teach Unity and many studios use it because it is what the incoming talent knows…which leads to college teaching it because it is an “in demand” skill.
BUT - I think that could change quickly as more studio heads become aware of Godot as a viable “free” alternative for smaller indie projects (studio heads and publishers are notoriously cheap). The AAA world already pushes Unreal, so medium-sized studios that want to appear AAA will likely jump on that train.
***************TL;DR: I won’t be buying any Unity stocks.