Do you have any data to identify which of the many thousands of Usenet groups are those which are most active?
If so, please will you publish a list? If that is too much work, maybe a list of the twenty most active Usenet groups?
Thanks if you can! 😄
You can do this yourself in the newsreader.
Just click on the plus sign at the bottom of the subscriptions list and choose "New Subscription".
Then a window will open with all the newsgroups supported by your newsserver.
In this window sort on 'Total Articles' (click once or twice on it).