Which UliCMS Version should I choose?

There are currently two versions of UliCMS available. Every version is suitable for users with other needs.

If you want a very reliable and proven long term supported CMS solution, then you should use UliCMS 8.

UliCMS 9 is better suitable for the users that want always to take advantage of the newest bleeding edge web technologies,.
It has many new features, but has shorter support lifetimes, so you have to upgrade your CMS more often.
Even it could be, that some features are not as mature as possible.

If you're familiar with enterprise Linux operating systems then we could say that UliCMS 8 is more like CentOS or Debian, while UliCMS 9 is comperable to Fedora.