I switched from OneNote to Logseq. Its feature set is pretty much completely different, but in the end I realized it’s fine with me and resulted in my notes being more useful.
The main downside that I see now is that it’s kind of slow - much faster than the Electron version of OneNote was last time I used it, but slower than old native OneNote app or Obsidian. Otherwise its main differences from Obsidian are that in Obsidian the basic building unit is a page, whereas in Logseq it’s a paragraph (and, usually, its sub-paragraphs - it’s an outliner), which Obsidian can only do with plug-ins and not as seamlessly, and that with Obsidian you pretty much need to use community plug-ins, whereas with Logseq a lot of the functionality is built-in.
It’s open-source and uses markdown, not completely standard, but close enough for the files to be entirely usable if Logseq ever dies. Its community is smaller than with Obsidian, which is a downside, but it’s not exactly obscure either.
Really probably the most important thing about Obsidian and Logseq is to read an article or watch a video about how automatic backlinking works. It’s especially useful for something like Zettelkasten, but it also works for more “normal” approaches as well as concepts like Getting Things Done.
Both are OK tools and are similar in many ways, but they’re quite different from OneNote. Downside of both is that synchronization between devices sometimes creates issues unless you use their paid service.
Imo it’s the latter. It didn’t start that way, but in the last decade they gradually shifted to being simply inflammatory on purpose because that brings clicks, and on top of that they regularly did dumb shit like complain about sexualization and male gaze one week (often, though not always, legitimately, but mostly it was literally just complaining without any further insight, which I personally don’t care bout) and next week publish an article with photos of top male bulges in some sport that, apart from the gender being swapped, was literally worse than what they complained about with regards to sexualizing women.
Personally I say good riddance, but I’m biased by a deep dislike for people who use identity politics to create divisive clickbait.