openbsd

Any of the BSD releases (NetBSD, OpenBSD, etc) are the most unix-like rather than linux. Before linux came out, BSD had been around, running parallel with a lot of the unix activity (lot of history here between SV5 and others, not mentioning it for brevity). It's really secure "out of the box" (this doesn't mean never check for updates) and if you get pretty good with it, you're just about 1 step away from being a unix administrator (file systems similar, etc). It's just daunting for complete newbies to try to learn because of its intricacies and complexity. A couple of years ago (I think, I could be wrong), they started the 'let's make linux compatibility with *BSD' so now linux programs are more easily compiled on BSD boxes and whatnot since the most 'open' of all the unix-like OS's (including unix) is linux. This is where all the development is currently (check out the GNU site for more programs).

Overall, if you're looking for best installation, I've heard great things about Mandrake. If you're looking for best support from a vendor, Redhat's the way to go (both online and phone support are very good). Want to fuX0r your system up? Try Slackware. It really boils down to what you want to do with the system. Just about anything that has a 'configure' script can be set up/installed on these flavors yet each one has its own set of pros and cons against the others.

Personally, I use RH 7.1 patched and I'm about to go to 7.2. I've been a RH junky since 4.x and it's done me good so far (that and ROM 2.4 doesn't complain too much, just against the random declare).

Hope this helps some and I encourage anyone who finds a flaw in this 'short blunt history lesson' to correct it, as I'm a bit lame on the whole history of how BSD came about (boss told me once but it was a combobulated story from hell).