Not sure whether to choose Unreal or Unity? First off we recommend trying both and see where your heart leads you. If you want more guidance than that...
Unity is amazing if you want to learn programming and you're a bit intimidated by it. C# is a friendly language, Unity has a simple interface and the asset store is great. There's a real natural flow for a beginner (which we've seen when teaching our Complete Unity 2D and Complete Unity 3D courses).
Unreal is beautiful and you can make amazing things. As a beginner it nearly gets our vote because of Blueprints, a visual scripting language, which is easy to use. You can make beautiful cinematic moments very easily and the Unreal marketplace has a lot of good looking assets.
The winner, for a beginner, is Unity (narrowly), if you want something that looks beautiful then it's Unreal.
Unity uses C# which really quick to compile, so great for iterating. Simpler to use, meaning you can progress quicker.
Unreal uses C++, which is industry standard and used by many AAA studios, so if you're interested in a career then Unreal has the advantage. It also has lots of built in systems so you don't have to buy as many assets, but this does make it more complicated to use.
The winner is Unreal, for advanced students, as all the extra code and systems will teach you more and learning C++ gives you a lot of power. That said, Unity is great for getting things done quicker and more streamlined.