Operating System (OS)
Every OS has its advantages and sometimes you need to work on a different environment. For the app development with flutter I used an apple device since the worker needed macos for building ios apps. I actually prefer a ubuntu machine for my private work. This website is running on a debian server.
Since C# was part of my everyday life (until 2015) i get used to visual studio which means windows 😉
Whatever os you are using in your company – count me in.