I've enjoyed working with Elixir and the Phoenix framework to create APIs and handle websockets communications. I find the Websockets abstraction to be very clean, and pattern-matching the message itself is both intuitive and easy to reason about. Ecto, the database-abstraction, uses a DSL that feels almost like writing SQL, both DDL and DML. Phoenix scales incredibly well -- a single (albeit large) server can handle millions of simultaneous websocket connections. Adding more servers to a cluster is also trivial, and built into the underlying OTP framework. The ecosystem is solid -- there's one prescribed test library, one documenting system, a release manager in Exrm, package manager in Hex, and build system in Mix. I really enjoy writing in Elixir, in a way I haven't felt since discovering PHP in 2001.
Operations wise, I find Ansible to be super easy to use, and very quick to pick up. It handles most of my mundane server operations at scale. I've not found a need personally to add Chef or Puppet in concert with it. I like the premise and promise of Docker -- all the benefits of Vagrant without the myriad problems we ran into with VirtualBox and Vagrant. I've toyed with it and like it, but do not use it for production use yet. I do think Ansible + Docker will make a mighty fine pair in the coming year or two.
Postgres has been my go-to database for about 5 years. With the recent addition of the jsonb type, we have much of the power of Mongo, but with the ability to to add relational data in the same storage mechanism. It's super stable, highly performant, and scales well (though the tooling around the scaling is a little lacking if you're looking for anything beyond read-slaves and/or partitioning, such as multi-master). With extensions such as PostGIS, and the ability to write stored procs in languages other than PL/SQL (python, even JS), it feels both extensible and modern. The main drawback I can think of is that the best-of-breed GUI is Navicat by leaps and bounds, and it's expensive and I hate the licensing setup(per OS, and per DBMS).
Frontendishly, I will admit I haven't done much of substance in a while. I enjoyed the power of Angular 1.X but it was definitely still maturing during my usage in 2013. I can see why people would pick React/Flux, and I've played with toy apps using that design pattern and library, but I can't speak on using it to build anything substantial. I like the idea of the one-way data flows in terms of reasoning about my dataflows, but you do need what seems like a lot more boilerplate to accomplish the same tasks as Angular. It's a tradeoff, but I couldn't tell you if it's worth it or not. My gut instinct says yes.
Sean Moore
Systems Architect, LookFar