In the page hit rankings over at Distrowatch, Slackware is in a free-fall and has dropped to number 20 and will shortly drop to 21 as Kubuntu moves up. Some of these distributions I've never heard of, e.g., Manjaro, Zorin, OS4, Bodhi and SparkyLinux. Even FreeBSD has moved up to number 17.
Frequently a lot of answers in here involve advising someone to compare distros at distrowatch.com. As you may know, the site has been down for a few days and here is a story with some explanation:
This indicates that for now you can still reach the site at http://distrowatch.org/
I found a thread a while ago in which someone asked about the rankings / titles used on these forums and corenominal replied. I can't find it again, despite searching for the last 30 minutes or so. Anyone? :D