Game development is, in my opinion, far too complex to have the efficacy of working in it attributed to a single language. For me it all depends on what type of game is being created and what aspect of said game is being worked on.
For straight-forward 2D or 2.5D games with no networking features I would prefer working with JavaScript/HTML5 because of the ease and simplicity of deployment, which makes up for the faults of JavaScript as language (and there are many of those). ActionScript, as a language, is also applicable because it's damn near identical to JavaScript, but I wouldn't choose it because it is tied to Flash Player. Should the 2D/2.5D game require some fancy shader effects, such as particles, I'd probably choose C#.
If networking were to be included then I would choose Python or C++ for that, depending on how much power/speed is required; many concurrent users performing many actions would definitely necessitate C++ but otherwise Python would probably suffice.
For low-poly 3D games I would probably still stick with JavaScript, depending on the situation, but for anything more complex I'd use C# or C++, the latter of which obviously only for cases where performance and quality are both high priority.
As for specific aspects of game development, rather than it as a whole, such as GUI or AI scripting, I'd go with Python, Ruby or Lua.
In summary, I can't say there is any language that is my favourite to create games with because game development is often a complex beast, and choosing the right tool for the right job is more important than choosing a tool based on preference.
Having said that, it's highly unlikely I would ever use any language other than: C++, C#, Python, Ruby, Lua, or JavaScript.