The authors of the the FreeBSD document don't make the version differences very clear. I am looking for which is the version of FreeBSD that is most stable, in other words, has software that isn't going to crash on me. I don't care about having lastest greatest features, or I don't even care if the software is more than a year old. Just that it works rock solid stable.

Best choise would be polished 6.2-RELEASE, since 5.5 is last of 5.X tree, and 4.X is unsupported now.

I wouldn't ever worry about that. If something crashes, it's a pebkac issue.

Which document is that?

At freebsd.org, under the large yellow-orange oval that says "Get FreeBSD Now", you'll see the latest releases. At the moment, they happen to be 6.2 and 5.5 (production legacy). If you're installing a new system, I agree with vermaden - go for 6.2.

As for tracking your release branch for critical bug/security fixes, you'll want to use the RELENG_6_2 tag. For ports, we all use the same tag (which is why I only update ports when I need a bug or security fix).

Unfortunately I also have to agree with the previous poster. If you're sticking with a -RELEASE branch and do due diligence with your port updates, the weakest point in the link will be you - the admin. (And I am certainly no exception to that rule myself.) FreeBSD itself will be rock solid.

Read the handbook and make life easier from the start. Hope that answers your question. Best of luck.