cryengine only announced it, without source access, but 9.9 per mo is neat (and I think they will limit the available platforms). ue4's cancelling option is also neat. I wonder how crytek improved the workflow to be more user friendly (and easy). the photoshop and Max/Maya dependency of cryengine3 was a significant gate imo. a few days ago a 3rd party importer tool appeared for it, probably a similar one can be expected for cry4.
due to my little testing experiences, ue4 is much more easier than UDK was (making a new project is not a pain any more, fine asset packs, example projects, templates), with good docs and videos, but still more heavy than Unity (I used only Unity3, which was really easy), whose javascript is as easy as lite-c. but 75/mo is now simply too much.