Unreal Engine 4 is now free. You can create what you want for no money down and only pay a 5% royalty on games and applications you release. For comparison, Unity has a free version of their game development software but also have a UNITY PRO available for $1,500 or $75/month. This move will definitely persuade people to chose the Unreal Engine over Unity and with Unreal’s new VR features those looking to develop VR applications should consider the Unreal Engine. Existing subscribers will receive a $30 credit towards the marketplace where users can buy additional assets created by community members. While the Unreal Engine is typically praised as being more powerful and user friendly when compared to Unity there are still some areas where Unity has slight advantages.
Source: What Is Unreal Engine 4