UE4 for mobile games, Unity if you need a mobile network game with options to extend the network. UE4 has the most fluidity and performance that you can have for your games, plus the various options that you get with it make it too easy to make games. The rest is streamlined so easily that you basically spend most of your time clicking and dragging instead of directly animating and coding. The thing that sold me to UE4 for mobile was that it was easier to setup and create a game on the fly compared to Unity.