I've personally always loved CRYENGINE the most. I've used both dev kits and CRYENGINE's is more fun and technically cooler.
When you look into it, Unreal uses more "fake" post processing and visual effects. Meaning a lot of the visuals aren't interactible nor do they update in real time. In CRYENGINE on the other hand, practically everything from volumetric fog and clouds to the particle effects on grass and celieng tiles is real time and interactive. Unreal is still beautiful, don't get me wrong, but in technicality and the technology behind it, CRYENGINE is the greatest engine available even over Frostbite (which isnt that great honestly. Lots of fake post processing like in Unreal).
CRYENGINE also runs better on most machines than Unral. The only reason it would be harder is because its Ultra settings are technologically superior than every other engine. These screenshots are kind of horrible for CRYENGINE. it looks as though there's no AA on anything!