TL;DR: macOS/iOS. My family introduced me to the original Mac in the 80s, but I was on C64. (Because colors and games. Of course.) Then switched to Atari for music production, but only for a short while, and soon returned back to Apple: chose a 68K PowerBook, because a mobile computer was extremely useful as a student… and finally managed to appreciate the Apple magic. Getting back into music/audio, the Macs grew in size: 7300, Cube, PowerMac, Mac Pro, but now also mobile again with a MacBook Pro. (But I have to say that the new 15 inch Air is quite awesome… even more so with the M3 soon.) So I’ve been on Macs for all my adult life, though there’s usually always a Windows machine and Windows Server at work that I have to struggle with and scream at. I’m an Apple disciple, for sure, but I can also see myself switching at some point, because Apple does have a way of continuously encroaching, tightening the screws, closing the gaps in the walled garden, not least of all with their security porn, both user-facing and under-the-hood… though until now I’ve always managed to find workarounds. But I wouldn’t switch to Windows. Anything but Redmond is a good choice: macOS, *BSD, Linux. I’m a borderline command-line junkie, so I don’t have any problems with the other Unix or Unix-like systems. I even bought a Pixel to install Ubuntu Touch on, but got stuck in the device’s firmware after first reboot. But yeah, Linux would most probably be my choice, if I were forced to leave Apple’s ecosystem. (I already have a micro server running Ubuntu Server, and a Raspeberry Pi with HOOBS for smart home stuff.) If I had to choose now, I’d probably go with Debian/GNOME with a nice Tuxedo notebook. But elementary OS is also pretty nice, feeling close to macOS in many ways. (Apple does, after all, still have the greatest Human Interface department, though it has been lacking a bit in recent years.)