depends at the level you want to work. UI/Web and hard to avoid JavaScript/HTML5 although Elm is very interesting.
Move lower down the stack and things like C++/C# are popular. I am a huge fan of C# over C++ although C++ still has huge traction.
Python is a great language but things like F# and Haskell are gaining ground. Facebook has one of the biggest Haskell stacks out there although they still run a lot of PHP (oompf I have just thrown up in my mouth) lol
All boils down to where you like to work and the languages you like :)
That's the complicated thing. I've been out of the game so long it's hard to figure out where to jump back in. I guess I'll take your advise and focus on what I really want to do with the language before going full steam ahead.
Best thing. I found I am happiest below the UI level, better fit with my mind. So my weapons of choice are C# and F#.
I have gone through all the normal Basic, VisualBasic, C, C++, Java, JavaScript, SQL etc before I fell in love with C#.
C# is a C style language with some great syntax and language sugar and no pissing around with memory management :)
Over the last few years though I found Functional languages and those I really love. I prefer ML style over Lisp style though as Lisp is bracket hell. I picked F# as it interacts with C# and .NET so a natural fit. I dabbled with Haskell which is one of the most beautiful yet mind melting languages I have encountered. Just when I think I have groked it my mind melts again and I realise I haven't. lol
I don't know if I'm more motivated or less after this. It just becomes so overwhelming haha. I appreciate all the info and I'm going to check out the one's I haven't heard of that you mentioned.