I'm running Slackware Linux.
Beryl/xgl or Compiz have been around a little while, but I've not bothered to try it out until now.
I've used Gentoo in the past, but always come back to Slackware for the stability and reliability. Gentoo is one of a few I would rank along with Slack as a top notch distro. (Assuming of course that the person who built/installed it knew what they were doing