I used org-mode for a while, but I wasn't an Emacs user, and using it just for that was not a great fit. No one ever says that, but let me say it:

If you aren't an emacs person, it is not going to be a fit.

Workflowy is a pretty easy-to-use web version of the outline part, which requires zero setup and the other features of org-mode I never got into. Other things extend beyond this into the PKM space ( Roam, Tana, etc ).

Also, Zettelkasten is an interesting thing, but more as a curiosity, some process that worked for a specific researcher in nineteen dickey two, not as some process you should use.

For me, the big great outliner was workflow. Roam improved on that, and things improved for Roam.