(Backend) Node.js: For extremely rapid prototyping Meteor.js remains superior, for everything else: Elixir. More complex Node applications tend to become fragile, unstable or awkward to read, and I'm (or: 'was') doing node in several flavors for years now. (express services , meteor apps, nw.js desktop stuff, scripting/automatisation, ... everything I can/could think of)
(Frontend) Backbone, Angular, React: Ember.js all the way now. It assimilates all the shiny features (web components, shadow'ish DOM, ...) and comes the closest to "developer happiness" imo. From all the SPA-frameworks I've worked with, Ember is the only one that doesn't feel wrong, unneccessary complicated or too DIY'ish.
(Database) MySQL, MongoDB: Doing Postgres now more and more, feels good.
(Misc) C, C++, Go: I decided to go all-in with Rust for when I want to be close to the metal. But i'm still in the learning phase here.
Why?
Left PHP because I lost confidence in the language. I cannot write 10 lines of PHP with out feeling nervous of the edge cases I have missed.
Also, some exchanges with the 'core' developers of the language completely convinced me that the language is not going to improve. Their behavior and competence felt like they are just 15+ year old kids doing programming language work on the side. And the community! I cannot think about that without throwing up. Over engineering and bike shedding is the norm. Even the so called community leaders are UTTER MORONS. Without exception. No. I am not exaggerating [1] and that is not the only one, just the most recent. Also, please note that I am some one who started with great respect for these guys...
That is my opinion formed by closely following everything related to php, mostly from /r/php for 4 or 5 years.
Regarding MySQL, I was one bitten by MySQL when it didn't allowed me to use the same temporary table more then once in the same query. So that left me with a bad taste. And once I tried PostgreSQL, it felt quite a bit simpler and seemed to be lot more capable than MySQL.
And if I needed to do something quickly, that I knew I could scale I would go back to it (no php hate here).
I have traded my PHP in for golang... It feels like scripting with static typing, and much better performance.
:-)