20 years of macOS
After using Classic Mac OS at school for some time, it took me several years to return to the Mac. It was 2004, and I was happy to discover Mac OS X 10.3 Panther. It was completely new and better. Been using it until today (not Panther, though) and will, for the coming years. Some behind the back usages of other OSes, but let him who is without sin cast the first stone.