I started to learn and teach Unity at the university few years ago. I liked the fact that there are many videotutorials directly from Unity creators. It was extremely easy to learn the basics. I liked also TOPICS section in this page: https://unity3d.com/learn/tutorials . You choose the particular topic and you find useful videotutorials for it.
But the very best tutorial is Roll a Ball - Roll-a-ball (Deprecated) - Unity Learn . In this tutorial you can learn a lot of fundamentals of the engine. I think it is the best learning material for begginers.
Now I am studying UE4 for few weeks. I can compare it and I do not think that UE4 is more difficult to learn in its core. But the problem is that there are only few tutorials where you can learn fundamentals so well as with Unity’s Roll a Ball or TOPICS. Yes, there are tutorials for advanced things but how can I understand them without basics?
UE4 developers should make something like “Roll a Ball tutorial” for beginners. I think it would be extremely helpful.
Now I recommend this: https://www.raywenderlich.com/771-unreal-engine-4-tutorial-for-beginners-getting-started