From my perspective, they are all derivatives of org-mode.
But I've tried to dive into Org mode twice in the past five years, each time committing a few weeks to learning it. However, I eventually gave up and returned to Logseq. The steep learning curve was the biggest hurdle for me. Between understanding Lisp, figuring out and choosing between all the possible configurations and workflows, memorizing the keyboard shortcuts, and working through YouTube tutorials, the friction and mental load were just too high.
Logseq, on the other hand, provided most of the features [1] I needed while keeping the barrier to entry much lower - far, far lower than Emacs. But LogSeq is by no means perfect; I fear it will become bloated at some point (e.g., I have no interest in flashcards and spaced repetition learning)
[1] Outliner; data kept local; journal; simple task management; easy to insert quotes, code snippets, images; backlinks; possible to attach files
M-x === hit x and the ESC key (of all things) at the same time?
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.
Zettelkasten is just an idea, and a great one. I don't know what you think it is, but all these apps - Obsidian, Roamresearch, Logseq, Org-roam - are based on that idea.
The goal of my notes is so far from this that I found the ideas interesting but unrelated to how I use Roam, etc.
I was used many tools, include Workflowy and Roam. For me, org-mode & Emacs is the best tool of all, no tool can compare.
Sure, learning Emacs and Org-mode is quite some journey. But it's absolutely worth the time and effort.
I even try different new things from time to time - out of curiosity, and because so many times before, I have felt like being stuck in a bubble. And so far, I have not found anything much better than Org-mode.