To be fair, at work I've used Debian a lot for servers, and it had worked pretty good all the time with very few exceptions. In comparison Ubuntu (which I know is Debian based) always breaks for me. It's amazing how I can always get stuff done in minutes in Debian but I always have a problem with Ubuntu. This is to the point that I would rather work with the botched in-house distro of Solaris I used on a mini mainframe I used to work with and maintain some 8 years ago than Ubuntu. Even with the weird customized vi/vim it had, that made life for me and the sys admin incredibly painful.
All that being said... Slackware was the distro that made me fall in love with Linux a decade and a half ago, and one of the reasons I'm jumping out of the Apple bandwagon is their recent tendency to make their machines more common-user friendly, but less of an "hackers" machine. Therefore, I'm tremendously biased regarding Os' and Distros.