Most of the time I am a Windows user. It is the operating system on my parents' computer so I am familiar with Windows software. Every machine I have then is Windows for their convenience.
Now, I have both Windows and Macbook laptops. I use a Mac for work and I have to confess that there are more advanced things. Now I know how to use it and it becomes my working machine, and the WIndows machine is for entertainment. It's still smooth for several weeks.
One morning, I woke up and realized that I had left Windows in sleep mode after hours of playing Overwatch. Seeing that I didn't have to run to get a Mac in another room, I turned on the Windows machine and worked on it.
And then I realized I didn't need to switch between machines. Anything on this machine, I can do it on another machine, even external hardware can work on both machines. That's when I realized I didn't have to choose 1 in 2.
Admittedly, there's still a difference between Windows and Mac. Mac batteries can run better than Windows laptops. It's also more flexible, arguably lighter than the iPad and the hardback books I carry. Macs don't have as much bloatware as some of my previous Windows PCs. When it comes to problems, contacting support is also easier than Windows.
On the other hand, Windows machines can run every game and still have the strongest hardware. There are more options on Windows machines than Macs. I also want to build something that suits my needs at a lower price on the equivalent iMac.
Here are some software I use on both machines. I use Google Chrome on all machines, spending most of my time working on Slack, mostly on the browser, but this app is also available for free on Windows and Mac.
Depending on the needs you can choose 1 in 2, or whatever
When I have to write, I work on Google Docs, also on the browser. When I'm lazy, I can use Docs on the iPad. The same for the G Suite. It is certainly a bit difficult when offline or inaccessible to the cloud, but I can still work in offline mode.
What about photo editing tools? Photoshop is available on both OS and I usually save photos on Google Photos or Dropbox. Along with Evernote, my photos and videos rarely touch directly to the OS.
Even boring things can be done on both machines: social networks can be accessed from anywhere or so is Spotify.
There is no doubt that there are always users with special needs to choose 1 of 2 machines. If you focus on games, Macs can become useless. But both OS are flexible when working with 3rd party software.
Now, the decisive difference to choose is probably only aesthetic.