I started to use Evernote many years ago, then it started to lag and just suck, switched to MS Onenote, it just didn't know how to sync, 8 chapters worth of summaries I had written from reading a book disappeared and that finally made me quit it. Google docs kinda work but has the worst UI for file explorer and too much like MS word and since it's not standalone app the tab gets lost among other tabs, where standalone app is easy to switch to visually and through shortcuts.
I now just create bunch of text files on desktop: todo, book summary, appointments, etc... and when I'm done with them I just move them into giant unorganized folder. I have found notes from 7 years ago this way. Sure if there was a native clean app to search through all txt files it'd be great. But not so bad tbh.
I'd prefer open source. But there is nothing even close to Obsidian, at all, or anything even trying. The plugins even work on Android!
I sync the folders with SyncThing.
I also now use BitWarden instead of a notes app for secure things like credit cards and combination locks. I used to save a lot of stuff it notes that I probably shouldn't have. Although, I could see myself switching to KeePass just because I have heard it lets you sync with SyncThing.