I have not used Joplin, but did write a few high-level thoughts on comparing it to Obsidian and Logseq elsewhere which I’ll just copy and paste here:

I have not used Obsidian nor Logseq as much as I’ve used (or developed) SilverBullet. However here are a few headliners, but the main difference may well be that in SB I’m really assuming that the target audience is technical enough not to be scared by the idea of writing a query, or creating a template.

A few differences with Obsidian: it’s fully open source and it’s a web app that you self host. It’s still markdown files on disk, but that disk is located on your server and they’re accessible from anywhere you have access to that server without having to do convoluted things like setting up (or buy) sync services (like you do have to for both Obsidian and LogSeq).

Obsidian tends to solve everything with plugins, whereas SB has more batteries included (although technically much of this is implemented as plugins that ship with SB itself) specifically: powerful indexing, querying and template support. Obsidian has Dataview and Templater, and some other plugins I think, but they’re developed by a third party.

Another difference difference would be UI minimalism. The number of panes and tabs in Obsidian dizzies me, although I know you can fold or hide all of them. In SB it’s minimal by default.

Compared to LogSeq: logseq is an outliner. You can do outlines in SilverBullet (and I do, a lot, there’s some nice shortcuts for this too: https://silverbullet.md/Outlines). However, SB is more of a wiki than an outliner. You don’t have to write everything in bulleted lists. To me this is important, because I also write my blog posts and other articles in SilverBullet and doing that in an outline is somewhat awkward.

But to be clear: Obsidian and Logseq are both great, and they’re more mature. They’ve been around longer and have bigger communities (so far). Try them out and see what you like.