Currently I’m using Joplin with Syncthing-backed file system synchronization. I’m pretty pleased with it, as I do like tagging- and Markdown-based systems.
I plan to upgrade to server-based synchronization, but before doing that, however, I wanted to see what other people are using.
Edit: So far I see a slight favor towards Joplin and Logseq, but I totally didn’t expect (and appreciate) getting so many different answers.
Yeah, handwriting can be added to Obsidian, but it’s a bit hacky and I don’t use it. As far as instant sync, it is solid, but expensive. Some folks use Syncthing but I couldn’t get it to work reliably so I but the bullet and paid for Obsidian Sync.