I don’t have that much arguments against cryengine since I never used the new one.
But since I am using UE4 I don’t need to think outside the box. UE4 is simple to use, it has a nice documentation and a lot of starter content and videos. It’s kind of easy to create beautiful content and all the systems are powerful (My fav is the particle-system). Another argument is that the community and developers are nice and helpful.