It very much depends on the application.

What is the size and scope of the project? What feature-set are we looking at? Anything realtime? Performance critical? Large team building components at the same time? Maintainability? Scale?

If you really must pick a one-language-fits-all (and i think this poll reflects this logic) it would have to be python.

So, choosing tool before job; python. But also, you would be an idiot.