I think if you ask ten developers, you'll get ten different rankings like this, with minor overlap :)
It's going to be really really really dependent on your field of work, your career experience and network.
I'm not even going to attempt to offer a top five list, because I'm sure it will be wrong :D
FWIW, I would not base your decision on what language to learn only (or even mainly) based on "what's the most common language in use".
There's more than enough work in the world in all common languages, unless you're talking about really obscure research langs.
There's also value in getting expertise in something more niche - because fewer people know it, you can make a bigger impact and have less competition. It's also a powerful status signal - if you tell me you enjoy working in "Python and Haskell" or "Ruby and Erlang", versus "C# and Java" I'll have a very different impression of you (as unfair as that may be).
In summary, I'd say, try out a few languages, and learn the ones that you enjoy the most and feel most productive in. You'll spend most of your waking hours thinking in it, you might as well pick something that is fun for you to express yourself in, rather than a language that you have to fight.