After Yggdrasil I took a short turn to Slackware (downloaded a lot of floppies), and then switched to Debian which I had heard nice things about - and I have been running Debian ever since.
I always get surprised at how complicated other systems (Windows, Mac OS X) seem to me, when I briefly encounter them. I guess it is the power of habit.
Here is a bar chart of the votes:
· http://koldfront.dk/misc/hn/os/data.png
(Updated hourly currently.)