The operating system of Macintosh computers used to be called Mac OS, then MAC OS X and now it became macOS. This means that the naming is consistent with the other operating systems of Apple devices: tvOS, watchOS and iOS.
For me, macOS is the main reason you want a Mac. In the meantime, there is also reasonable hardware for Windows that you can work with reliably, but even after many years of development, Windows has still not achieved the intuitive user interface that you find with macOS. In addition, macOS works very reliably - at least for me - and crashes are extremely rare.