Kubuntu for a nice easy setup. It's my 'workstation' OS. In case you didn't know... Kubuntu is just Ubuntu but with the KDE desktop instead of the Gnome desktop. I prefer the KDE toolset for general desktop crap.
Redhat Enterprise Linux (RHEL) for running a server (a real one) because it's nice and stable and has Redhat support. For home stuff I just use Kubuntu or CENTOS (free RHEL but not supported by Redhat)
Gentoo because it's EXTREMELY customizable. I almost NEVER use this distro though because it's a lot of work. I've toyed around with it though to make a firewall out of an old PC.
Damn Small Linux (DSL) and/or Feather Linux because they'll fit on a 512MB thumb drive and they're amazingly powerful for their size (nice GUI desktop and everything). I use this on the road, or to repair my other boxes (just boot to the thumb drive, mount my hard drive and edit away). Similary, Knoppix (and lots of distros based of knoppix) will boot off a CD. This is incredibly useful to test a box to see if it's 'linux compatible' before reformatting the drive. There's nothing like formatting your windows away just to find out your video or sound card is unsupported by linux.
Edubuntu I've just discovered recently. It's a fork of Ubuntu with a ton of children's educational games. I recently installed in on an old hoopty machine and my nieces absolutely love it.
One that I don't personally use but sometimes recommend to others is freespire. A distro called Linspire which usually costs $40 is also available for free (hence, freespire). Anyways, it comes with things like mp3 codecs already installed which makes life a lot easier for newbies and/or for people who aren't interested in dealing with getting mp3, windows media, etc.
Edited 1 time(s). Last edit at 12/10/2007 07:26PM by Rade.