See, it's not about the engine but who is using it.
This is absolutely true but keep in mind that a professional studio has a lot of options. They are more open to different scripting languages and to different technologies compared to a hobby user who is often afraid to learn a new technology or to learn a new programming language / sdk. So they often use the tool that fits best to their needs or they use the tool that supports all the needed platforms that are suggested by the publisher.
All features people are whining about is available on UDK, go use UDK you won't do any better.
This is also true when you have a beginner or a small hobbyist in mind. But even advanced hobbyists or small indies will realize very soon that this actually depends on your project. When you want to make a huge indoor world then you will see that zones and portals are a big advantage. You will test a prototype and you will see that there are differences. Indoors work fine in C4 because of zones and portals, they work fine in Unity because of the Umbra Occlusion Culling and they work even better in UDK because of the great level compiler culling with the help of the good old CSG techniques. I also tested Vision3d from Trinigy and they use manually created portals as well and they even create zones automatically from the given potals.
And if you want to make it pretty you will see that you can combine static lightmaps with dynamic shaders easily in Unity, Vision3d and UDK. You need a lot of workarounds and researches to do the same in C4, Irrlicht or Gamestudio as an example.
But when you want to make a platform game, jump and run, puzzle, match-3 or and adventure on Windows only, then it is a complete different story. So it really depends on your needs and on your project.
What I want to tell: Dont generalize something like that! A team can really perform much better with UDK when they create an FPS shooter with large indoor areas. And they probably will only suceed on iPhone and Android when they switch to Unity (or when they create their own tools for that). But they can also create something great with Gamestudio when they accept the limits of it, though the same counts for everything else like Ogre, Irrlicht, Darkbasic, Neoaxis and co. And as you see from the list of available alternatives: A technology has to be competitive to attract more users than the other ones.
