Millenium on 19 June 2012
Simple: Everyone knows how to use it by now, it's "cheaper, Epic actually supports it 100% and it has a enermous amount of documentation.
CryEngine 3's available documentation is piss poor in comparison, is more expensive and less friendly to access to (I'm not sure if the devs that license it have the same issue, but the free sdk version has a bloody drm system where you have to be online and sign it to use it -.-)
The only thing CE3 really excells in right now is lighting and terrain system, which is set to change with Unreal Engine 4.
