Surprised to see so many people using Linux - very different to the Ruby world where most people seem to be using OS X.
Arch Linux + i3 WM, what else?
OSX 10.10.5 (using vagrant linux box for phoenix dev env). Haven’t made the switch to El Capitan yet.
Windows at work.
Ubuntu / Debian
Linux Mint Cinnamon
Ubuntu Linux 14.04 using GDM and i3-WM.
Sometimes I do have to do some university-stuff under Windows¹, but then there is always a Virtualbox running a Linux for everything else.
¹ I have to do a small Delphi-Project during the weeks between exam- and lecture phases every semestre.
OS X 10.11.3 (El Capitan)
Dabbled with them all settled with OS X.
(This is an important security notice for Mint users)
Debian testing which is called stretch for now. And there is one inconvenient thing about it: one have to use packages from 2 different branches (sid and jessie) to install erlang-esl and elixir properly.
ubuntu as virtual maschine on my desktop,
and a cloud9 workspace on laptop
I am a longtime Linux Mint user (Cinnamon) but have recently switched to Manjaro (based on Arch). I like the access to newest packages and the community packages on the AUR save me a ton of time building various packages from source. Not as novice-friendly as Mint but a great distro for experienced Linux users (I use Cinnamon there too).
Arch Linux + Xfce
I’m split about 50/50 between OSX on my Macbook Pro and Arch Linux on my desktop
OSX El Capitan, and occasionally ubuntu.
OS X (Macbook Pro) + Win 10 (HP EliteBook 840)
Ubuntu / Debian
Developing FreeBSD / MacOS … Testing Servers are Ubuntu-14.04-ARM Server
Ubuntu 14.04 on a DigitalOcean droplet, with tmux. That way I can dial in from whatever machine I’m on and pick up where I left off.
OS X El Capitan version 10.11.4