In my experience with open source projects, STABLE should be first on the download list. RELEASE should really be labeled release-candidate, with stable being considered the release.
RELEASE is the release, -STABLE is the minor branch for bugfixes and minor new features that don't break backwards-compatibility ("stable ABI"). -CURRENT is, well, current - it's the tree the developers are working on, and is the current state of FreeBSD, where releases are archives at a particular point (more-or-less).
I suspect much of this goes back to when development wasn't quite so public, so these are names that are meaningful to the developers, not the public.
Three key words there - "In my experience". Well now you've experienced a project who doesn't fit your current model of the world. Should those of us who have RTFM and experienced different vocabularies adjust to your model or should you recalibrate?
