TikiWiki 1.7.x is not secure and is no longer being maintained. Admins should adopt 1.8.6. (Old policy: Receives only bug fixes and security fixes.We do not add any new feature to it, nor backport any new feature.)
TikiWiki 1.8.6 should be used in production environments.
TikiWiki 1.9 may be used in production environments, there's lots of value added compared to 1.8, see ReleaseProcess192.
TikiWiki 1.10 alias HEAD is the
developer version, major new features go there.