At the end of the day any of the languages listed above get the job done for all but the most demanding of applications (if you are building the next google, you'll want to look at something more scaleable like Go or Haskell). - PHP is ubiquitous and can do almost anything you want if you can get past how weird the syntax is sometimes. - Ruby is a breeze to develop on when you use something like Rails. I hear its slow although I can't speak from personal experience. - Python is fairly easy to pick up on syntax wise and gives a lot of power right out the box - NodeJS (my personal favorite) has a vast community and excellent tooling support. It's probably the easiest one to pick up since everyone knows javascript but it has the downside of making it very easy to write awful code if you don't know what you are doing.

I've been writing mostly js for my few years as a programmer. Managing databases and building everything from scratch with node.js was beginning to feel very cumbersome. The full stack frameworks like sails.js did not have community. I still love node but these days I'm learning how to make Laravel apps with PHP.

While it's good to specialize in one aspect of development, the pendulum is swinging back the other way in favor of those who are more diverse in their skill-set. Don't limit your self by just focusing on one particular part especially in our profession that evolves every 6 to 9 months.

I would suggest HHVM since you already know PHP and also Postgres as a DB

After you have mastered your first language I think it's a good idea to learn another one and a few more if you have time. And as you become more and more experienced you'll find that learning a new language becomes easier and easier as the fundamental (low level) concepts in computer programming haven't really changed - just expressed differently in different languages. This will enhance your problem solving skills as you'll learn different approaches to solving the same problem.

Agreed - mastering a language well is crucial, and that can take years - and even after that, you can still get surprises.

Learn a new language/framework/library/tool every now and then. This is good for getting inspired, learning new patterns, new concepts, etc.

Don't follow the mainstream just because of f​ollowing something ;-) Do what suits you.

I think focusing on one language is really critical. Since I can use JavaScript pretty much everywhere; server to client. It looks like isomorphic js apps are the future so its a great indicator that JS is the way to go.