At least three reasons why I prefer (reason I can think of right now) that prefer Safari on macOS is the SMS/Messages integrations for sites still using SMS for 2FA, pinch to show all tabs (useful if you have a lot of tabs open for some reason), and private browsing is exactly that, if I open Facebook in a private window and login, open a new tab and go to Facebook, it doesn't recognize that I am logged.

Other than that, I love Firefox. I switched an automation we had using Chrome/Chromium to login to the site to Firefox because every time the Chrome browser binary updated I had to download a new version of the webdriver.