Disclosure: I work at a competitor note-taking app called Notable [0], so I'm somewhat biased.
I've made a comparison table [1] comparing Joplin and other popular note-taking apps, you may find it useful.
Joplin could have been my go-to note-taking app, but IMO they made a few bad design decisions and there are few things I really don't like about it, maybe listing some of them from my point of view could be useful either to Joplin's maintainers or potential users:
- Notebooks are indefinitely nestable but tags are not, why?
- Joplin's icon is SO out of proportions, it looks way out of place in my dock, it may sound silly but I might not have used it just because of this alone.
- There's a button for opening the current note via a third-party editor, this is quite powerful because it means you can use all the fancy plugins and capabilities your general purpose text editor has, but why are all metadata about a particular note stored who-knows-where rather than putting them in the note itself as YAML front matter so I could have edited them directly too?
- Attachments are stored on disk as plain files, that's great because now you can find them and edit them without going through Joplin if necessary, but those files are named with unique ids so actually finding the files you're looking for will be a problem.
- And why not storing all notes on disk directly too, so that you could have done fancy things like running a global search and replace on them, run git on them...? Storing them in a database is generally better for performance, but you can do both.
- Notes have a separate title field, why wouldn't I want to write my titles in an H1 heading in the Markdown content directly instead? The default notes look a bit silly because of this, coming effectively with 2 identical titles.
- The UI looks pretty ugly, there are too many buttons, the interface isn't properly responsive (at some widths the toolbar gets cropped, labels spawn multiple lines etc.), useless things like the "Watching..." label are displayed etc.
- The database location is not customizable, if it were you would have the ability to store multiple notes collections separately, and you could achieve synchronization for free just by putting your database inside Dropbox for instance.
- Some shortcuts are weird and/or missing, for example there's a shortcut for cycling between previewing, editing, and the split editor. That might be useful sometimes, but don't people just want to toggle between editing and previewing or between previewing and the split-editor most of the times? There should be shortcuts for doing that instead.
[0] https://notable.md
[1] https://github.com/notable/notable#comparison