Are you sure? It plenty of times corrupted my scene out of nowhere :/ The worst I got with UDK was "link broken, cannot save, blah blah blah" which is solved with a simple sanitation of your assets or making copies of what it's linking to, in the base package. With CE3, it refused a couple of times in opening a scene for…
Why not try all of them and see? For a quick summary on the other hand: UDK: Graphically, it's everything an artist, quick prototyping is pretty OK with Kismet and it's co-tools like UScript. Real problems starts when you want to dive into more hardcore stuff, even if you buy Source-Code, it's been said it's far from the…