Prefer if you gave me the top 5 choices, from the best to least best.

someone did a poll to see which distro was best for a server similar to the one you might be setting up. now of course the results are biased towards slackware, because many people on LQ use it. i too think slackware is a good, stable, reliable distro. but you can look at the results to see the rankings people gave on this site.

now for my opinion: if you want an ultra-stable, ultra-secure OS, i'd go with OpenBSD or another *BSD. so i guess if i HAD to rank the top 5 in my opinion, it would be: OpenBSD (check them out), FreeBSD (i personally use it), NetBSD, Slackware, and then Redhat (a lot of people on LQ seem to use this for a server, so it must be good?). BSDs are amazing. many have several year uptimes, and Yahoo! uses FreeBSD (maybe not anymore?).

From the panel on the left, I see you have Suse 9.1 installed. That looks like a good one, as it's already installed. The only difference between distros really, is admin tools specifically developed for that distro, like MCC for Mandrake or Yast for Suse and the package management tools. The kernel and the packages themeselves are the same under the hood. Go with what's comfortable.