I use both–in my experience Unity is very easy to get started with but that’s because it lacks many features. When you start getting into things more Unreal has more complete systems–with Unity you have to buy a lot of things from the asset store, for example the UI system in Unity is very limited. Unity has two advantages–one is the asset store which has many useful things and without which the engine would be pretty much useless. The second is that it’s very easy to target low-end systems, and that’s mostly due to the lack of features. When targeting low-end systems the disadvantage with Unreal is that there are some settings in config files that you might have to mess with and there’s stuff like post process FX that are on by default that might be slowing things down as well.