Deciding on a game engine is a difficult choice. I have only looked at two popular potentials due to them being widly used worldwide and offering varying free licences. This makes the process of learning the engines better as there is no financial loss when using the program enitially. The two competing engine options are Unity or Unreal 4. There are many other options regarding game engines but they usually require finanical dedication in order to have any acess to them.
Ureal Engine 4 (UE4) would have to be my personal favourite based on it being a full program that has been developed with the artist in mind. Its 'Blueprint' scripting makes it so that developers with little code language knowledge can actualy get started... really they can without knowing any code at all yet still produce complex actions within the game. With the full features being presesnt it means the user can create a game that graphically surpasses anything on the personal version of Unity engine (however Unity Plus or Pro enables competetive visuals). UE4 is however extremly demanding on most machines that do not meet the specifications.
Unity Engine Personal is another great free option, however it is not as powerful as UE4. You are limited to certain types of lighting features such as limited shadow castsm and a few other things that can stop a personal user from progressing visually to a AAA standard without paying for advanced features. Unity however does come with alot of help from Unity Technologies and some other third party individuals regarding learning materials. There are hundreds of hours of free courses to learn from which include using Unity as well as detailed descriptions on how to use C# which is the main scripting language for Unity (if you wish to have more interactive function within your game). However this is also the case with UE4 and Blueprint/C+.
Based on the demanding specifications of UE4 I have decided to use Unity Engine for this coming project due to my Mac being unable to perform with high end graphic content. (Test was done using both engines. Unity works well on Mac depending on asset content. UE4 runs extremly slow on low-mid settings on my Macbook Pro without assets). However in the future I will be moving to Unreal Engine for AAA game practice.