Ubuntu 8.10. My XP install had gotten corrupted and I didn’t own a disc copy of Windows. One of the tech support ladies at my school gave me a copy. Once I discovered the desktop cube and GTK themes I was hooked.
Ubuntu, then Mint, now Arch, but I’m too inexperienced for it and want to try Kubuntu for native KDE with Plasma desktop.
*ubuntu (Xubuntu -> Ubuntu 10.04 -> Kubuntu 12.04) -> Debian 8 (KDE). Debian since then.
Opensuse ca. 18 to 16 years ago
SuSe Linux in the early 2000s. Came on a couple of CD-ROMs. We used it to run JBoss servers at work, alongside various Unix flavours. But my first experience with Unix was in the late eighties at university. Been using Mint as my daily driver for about two years now and I’m never going back.