I use Mac/Windows probably 60/40 (Mac at work, Windows at home). For the vast majority of the time I’m in Chrome or WebStorm or Outlook or Evernote or Git Bash and the OS is irrelevant (except the clock is in a different spot).
A few years back Windows was a real second class citizen in web development circles, but now there isn’t too much that is OS-specific (although macOS with Windows VMs is easier than Windows with macOS VMs).
If I was getting a new laptop today I’d pick it by the hardware (preferably ridiculous RAM and a touch screen). At the end of the day, the OS doesn’t really make much difference.