The reason why so many software programs are available is because the subject isn't understood very well. Well known programs for making notes are a plain text file, Onenote, asksam, jabref, endnote and many other programs. To summarize the information we have to introduce the software category of a two pane outliner.
A two pane outliner is some sort of defacto standard for creating notes. If a certain program tries to reinvent the wheel the tool has to explain why it is not an outliner but something else. Most existing programs like Obsidian or onenote are indeed normal outliner programs which are extended by additional features. So let us first investigate a typical outliner program in detail. The Treepad outliner is a good example program. The program is no longer available but for historical reason it can be seen as a good example.
Treepad was available for the windows and the Linux ecosystem as well. It is showing a gui to the screen which contains of the two pane layout. In the left window the structure of the document is shown, while in the right pane the text itself is presented.
It should be mentioned, that an outliner is different from a text editor, from a database and from a word processing application. It has little or no layout features, and has a strong focus on full text search. In contrast to a text editor, the user is investigating a very long document which contains of hundreds of subsections.
The outliner concept is so powerful, that it is hard to imagine a possible alternative. The same outliner program can be used to store different sort of information like source code, notes, and even bibliographic information. At the same time, the term outliner is seldom used in the PIM and note taking community. Why?
One possible explanation is, that most note taking apps doesn't see themself as an outliner but as something else. The paradox situation is, that this self awareness doesn't match to the reality. A closer look into note taking tools in the now and from the past have shown that most of them are outliner programs. Let me give an example. The asksam software which was very popular in the 1980s and early 1990s has described themself as a full text database. The reason was, that asksam was able to search in the content at very fast speed. This was the unique feature of the software. BUt a closer look into asksam will show, that before the content can be searched it has to be created. Ant his is done in a hierarchical fashion.
The inofficial successor of Asksam is the myinfo software. Myinfo looks similar to the mentioned treepad software. It is a normal outline editor which includes the ability to search in the text. It is the same sfotware category like Cherrytree or notecase.
Another interesting situation is, that larger programs like Obsidian and Onenote are avoiding the term outliner. THese programs are looking different from an outliner, because there is no left pane with the outline available. It needs some extra clicks in the GUI and in case of Obsidian the user has to install a plugin to make the outline visible. But, all these programs are asking the user to create sections. Otherwise the content can't be stored. So it is an outliner for sure, only the left pane is not visible.
The Treepad software was available from 1995-2019 and then the project was terminated. The major advantage over other note taking software was, that treepad defines themself as a two pane outliner. It was described in the manual what the inner working is. The user has to create sections which are visible and then he can enter text. This is the core principle of a note taking software. And the concept is so powerful that other programs apart from Treepad are working with the same idea in mind.
It is important to understand that note taking is equal to use an outliner program. No matter how the software title is and what the self understanding of a certain program is, all these tools are nothing else but ordinary two pane outline editors.