Nowadays, my system is a Debian Sarge (stable) and it is a GNUStep/GNU/Linux system. Windowmaker + GNUMail + ProjectCenter + Gorm + TextEdit + GWorkspace + Pan + TalkSoup + AddressManager + Cynthium + Terminal. It's not my usual set of utilities, but I'm finding it to be very very good. I'm comfortable with it already, and I think it just might work for me.
In addition, I am already sitting comfortably on the apt system of debian. I had a working system that I liked and was relatively stable in less than 30 minutes. I don't know about you, but that's fast. I was amazed how quickly I got it all installed and ready. GNUstep works flawlessly with Debian.