Vista. Tried to make Ubuntu work for a while but that was a shit show back then… Moved over to OS X and I was home - a beautiful UNIX where everything just worked. Stayed there for close to a decade (Lion-Mavericks-El Capitan-High Sierra-Mojave), mostly on non-Apple hardware.
Sadly, the iOS-ization ramped up so I had to rip tons of iCloud related stuff everytime I did a fresh install and then Catalina killed off 32-bit apps and brought other irritants, so I tried Fedora 35 and escaped with close to no issues.