As an open-source alternative, Joplin could be worth a look. It's a little different in terms of features, missing a lot of the linking which is kind of key to Obsidian's appeal, so maybe it's closer to Evernote. Still, they're fundamentally the same in terms of being a note-taking app built on folders of markdown files. It's quite actively maintained and improved too.
Joplin is my choice too. I deplore the complicated codebase, unfortunately. I would have made the changes to get better linking, at least in a personal fork, but I could not find the time to commit myself to it.
I’ve been using Joplin for about a year now too. My favorite feature is the totally seamless cross-platform sync. Honestly if Obsidian had better support for sync on e.g. Dropbox, I would’ve taken the plunge.
Joplin has its issues though. For instance, it seems confused about the format that it wants to store your notes in. Desktop search recently became useless too (no highlighting of search terms and ranking is broken).
Also Joplin's mobile app is poor compared to obsidian's, and that's with obsidian basically just shoving the same content as in the desktop app into a mobile web view.
Joplin is great, simple, and I love it. I find things like connections and tagging to be more work with minor, if any benefit. Just folders with markdown works great.
