I saw that people mentioned oceans and stuff like that, so first we have the recently released water examples by Epic which you can download through the launcher and second, for those who need an ocean with bouncy-movement and so on, take a look at this thread: Community Ocean. and the others created a nice ocean plugin, which even comes with underwater fx and fish schools in the last version I saw.
And to give my own feedback: I tried CryEngine 3, Unity 4 & 5 and UDK/UE4. The best experiences I had were with UE4, also thanks to the community. UE4 is a great engine and Epic as well as the community work hard to make it even better. I see no reason to switch to another engine, since I get with UE4 almost everything I want, and things that haven’t been realized are coming. Real-time dynamic global illumination? Coming with 4.8, or you can use either Nvidia’s VXGI or’s solution as soon as it’s released. Missing some BP nodes? Look at 's VictoryPlugin, it might have what you need. These are just example cases, but overall I see no reason to not stick with UE4.
Greetings,
Dakraid