Being very young I remember getting a magazine with SuSE 6 CDs and was so scared of installing it and losing my Windows 95 installation, at that time I didn't know how to partition a disk. One day I just decided to go for it but since my knowledge about OS wasn't very good and being confused with the GUI, I went back to Windows.
Later on, while taking Operating Systems as one of my subjects in university I came across RedHat 6 and went all the way to RedHat 9 while maintaining PCs for the OS and Networking Labs, but Debian was poking my mind...
So I tried RedHat 9 on my personal PC and was able to dual boot so I felt more confident, but... my PC would freeze 'cos of some bug making my NVIDIA card and Xorg crash, so RedHat went to the trash can after many tries of recompiling the kernel and using different booting options.
It was time o try Debian... failed...didn't know what to do with so many CDs and got lost with apt-get ... lol .
Ubuntu 5.04 came to town... w00t... it was MAGICAL!! things worked out of the box, since then I've been with Ubuntu, skiping some versions here and there, and now I'm thinking on moving to Mint to keep it simple since Ubuntu has changed so many things that not interest me.
In production environments, the companies I worked for would use RHEL/CentOS or SuSE, to that I have to say, it's my impression RHEL/CentOS has more support from the community, but SuSE has YaST :-) which made my job soooo easy.