I’m currently using Unreal Engine 4. It’s excellent. But any game engine is a whole new set of skills to learn; most ID folk aren’t going to be used to the idea of needing to “tell” the engine to give an object reflections, for example.
We had previously tried CryEngine 3 and the results are incredible, but it’s the shaders that made us switch to Unreal. Its latest version has a BSDF style of material creation, which is more related to conventional rendering. So this allows me to easily recreate materials I’ve already made in other programs. To me, CryEngine’s gaming-style system is much more difficult.