Linux, because it runs Docker naively. Docker has been a game changer for my team's productivity; we are able to switch between projects and run a full development environment with little effort. Docker naively on Linux is a lot nicer IMO because there is no VM performance hit (such as on OSX or Windows) and INotify works for detecting code changes when code files are mounted into a container (need a Polling file watcher when on a VM in OSX or Windows).

Before buying new hardware, I ensure that it is Linux compatible. I go for Intel WiFi, integrated graphics in laptops, and ensure that the screen either looks fine at native resolution or 2x DPI scaling, since decimal scaling on Linux still has a ways to go. This usually limits me to 1600x900 or 3200x1800 on a 13.3"-14" screen, or 1920x1080 or 3840x2160 on a 15.6" screen. I don't plug an external monitor into the laptop (I've had too many issues with DPI mismatch, screen detection, etc.), instead I use a Desktop when at the desk. For desktops, Intel NUCs work well and a 27" 2560x1440 screen is great.

I maintain a dual-boot of Windows so that I can use Office and other programs that generally work better on Windows.

I'm on Windows 7.

The company I work for uses Win7, and I don't see it changing anytime soon. Several of my colleagues uses some flavours of Linux, and have been encouraging me to switch too.

There are a couple of reasons why I haven't switched:

- IT only officially supports Win7, so I'd have to be my own sysadmin.

- The guys running Linux also require all manner of workarounds to access their email and other systems that use Active Directory.

- Libre Office and MS Office documents don't always render the same, as one poor fellow recently found out when he had to do a presentation.

At home I use whatever I like. Currently it's Mint.

Linux. The range of tools is unbeatable, and the price is right. If that weren't enough, almost every thing is open source, so you can see how it's really done. That can be unsettling in some circumstances, but on the whole it's a good thing.

Also: X11. There's no comparison with competitors in terms of variety of every single tool, and the customization you can do with it.

Mac OS for Python, Go, JavaScript. Primarily for combination of GUI and command line. Large set of tools. VMWare instances for Linux and Windows for final build/testing and deploy.

Currently using MacOS, mainly because I work as a iOS developer.