Having started with Joplin, the three things that took me away were the (at the time) lacking mobile support, periodic syncing collisions, and probably most importantly, their non-standard file format. There was a tool that could extract files into standard markdown format, then repack them, but the overhead was tiring, and meant a few key environments lacked access, namely when I was accessing a server from the rack, and when the mobile app acted up. I actually moved to just using vimwiki style setup with markdown and a markdown editor app on my phone for several years, before I stumbled across Obsidian. I've since been using obsidian for about 9 months now, which is longer than my time with Joplin, and I will say that, once I got a stable sync going (I'm using the simple sync plugin and my own s3 compatible server), the plugin support, decent mobile app, and native markdown files have won me over. Though I'm still eyeing open source options with Logseq, just waiting on their mobile app to pick up and properly support plugins. I'll be more than happy to port everything as soon as it supports that.

As an additional note, I will add that despite Obsidian being closed-source, I actually feel more comfortable with my data there than with Joplin, primarily because all my data is just common markdown. With Joplin, if I archive content, I have no guarantee the notes on the file format will exist in 10 years (they probably will, but it's still a real possibility). With Obsidian, it's plaintext. There's nothing to need to rediscover, no file format to decode, just good old plain-text. In 40 years I'll still be able to read those files (though the storage media is a very different story). Sure Obsidian can change plans mid-stream, and I don't trust they wont, but all I gotta do is go back to my markdown editor and vim. No sweat.