Unity Tutorial For Beginners overview has experienced in this tutorial. Unity is based on C Sharp whereas Unreal Engine is in C++. Usually, C++ is more popular in terms of video game designing than C#. Especially in the case of bigger projects.
At the same time, Unreal Engine has got the blueprint scripting system which is a lot more beginner-friendly. Especially for those who are new to scripting, considering its visual advantage. At the same time, if you get advanced in a programming language, then you can do a lot more in Unreal Engine. So, both for beginners and advanced users, Unreal Engine seems like the better choice.
However, Unreal Engine’s system requirements are too steep compared to Unity’s. When it comes to the marketplace, if I am not wrong, then not all of Unity’s assets are free. But those which are free could be used in commercial projects without any royalty fee. But Unreal Engines’ assets are free but they come with a 5 to 10 percent royalty fee in commercial projects.
The best tutorials are the ones that make you make games. As long as after each game you make your own with that same knowledge.
As far as beginner goes, the first three on the unity website are solid. Roll-a-ball, space shooter, and survival shooter. They’ll teach you the basics. Once you have those down, pick a project and do it.
Personally, I would start with Unity official tutorials. They are really good. Start with the UI and learn the ins and outs of getting around and a basic understanding of the editor.
Then go from there. The survival shooter was a very well-done tutorial that touches on many aspects of game dev with unity, but it isn’t overwhelming.
I’m assuming you have some programming experience. If not you’ll be extra lost even through beginner tutorials. If that is the case I’d start with some basics of C#.
Also do watch youtube videos for unity tutorials, many good ones out there.
Along with all the other great answers, and just like Mr. Wu has mentioned, I really recommend coming up with a simple game idea and trying to develop it by yourself. You will stumble upon many (MANY) obstacles, but that’s perfectly fine. Try to solve problems on your own, then once you feel like you’re stuck, find a tutorial (YouTube or Unity’s website) that teaches you how to solve that problem.
If you do that, you’ll have a better understanding of what the problem really is, and you’ll become a better problem solver, which is a skill I think is essential in any game developer/designer. This should lead you to understand Unity and how it works, at least that’s how I did it.