Debian on my servers, Ubuntu w/ XFce (a.k.a Xubuntu *shrug*) + Windows 7 on my laptop.
I usually stick to Debian based OS'es but I am no stranger to Gentoo, Suse, Mandriva, Slackware nor Redhat/Fedora/CentOS.
SteamOS is apparently going to be based on Debian as well, which is neat for me as I know how to tweak it to my liking.