Softlanding Linux System was the first Linux distribution I used. I had it copied onto 5 1/4" floppies from an acquaintance through the university. Slackware - which emerged from it - I naturally only smiled at and ignored as a high-tech user, as it still used the outdated a.out executable format. I switched quite early to Debian (still a 0.9 version) - but I have been consistently loyal to it only since version 1.2.
On my desktop computers, all kinds of systems - and unfortunately far too many PC systems among them, as I didn't have my Mac from the beginning. So I struggled with OS/2, various Windows versions, and again and again DOS with all kinds of multitasking add-ons (Desqview was cool).
Exotics also got a chance: with the Mac, I also tried BeOS for quite a while - but the software offering was too boring for me. And on the PC, the weirdest thing was a stripped-down Windows 3.1 of mine that served as a bootloader for ObjectWorks (which merged into Visual Works) and then managed my system in Smalltalk - but it wasn't a solution either due to the system break.
Linux on the desktop? I'd rather not. At the company for a while, at home also from time to time (also on a Mac), but somehow it never really clicked. Too spoiled by the Mac, I think. Although it's strange - because especially for Linux there are the most programming language implementations, and programming in exotic languages has remained my favorite game genre to this day ...
Servers? Since Debian, only Linux. 9 years now. Although in times of Apache+stuff, it has almost become irrelevant what runs underneath. It's also strange how we have achieved the holy grail of programming - fully portable software that doesn't care about operating systems. Completely without Java, by the way. The new desktop is the web browser anyway.
In my professional career, there are also things like MVS system programming in Assembler and longer years of Cobol slavery. But I'll spare us the links ...