You need to list out your requirements. What do you want to do? Where do you need your data? Do you care about open source? Self-hosting? Do you have an idea how your content will be organized? Will you ever need to tap into it as data? Etc
Have you tried trilium notes? Not as hyped and polished, but does extraordinarily well IME.
I didn’t like obsidian’s lacking in attributes structuring/typing and the fact that it cannot serve over a web UI (for wherever you cannot install the heavy client or just to share notes via URL), and found trilium notes to be doing that perfectly, and much much more. Highly recommend.
Neither XMPP nor Matrix will ever become “the next WhatsApp”: the current internet has seen too much consolidation for the tech majors to permit it (and open and federated protocols can’t compete, do not have the marketing budget nor the platforms to promote their software, but I salute the EU’s Market Act attempt to shake-up the status quo).
But that doesn’t really matter IMO. What (I believe) is important in the grand scheme of things is that such protocols remain alive, maintained and secure, so that:
small-scale instances can flourish and contribute to a more resilient/efficient internet (think of family-/district-level providers ; this is the kind of service I personally offer: family members and friends at large appreciate that the messages and data that we exchange aren’t shared over some cloud or facebook server for no good reason)
IM identities can persist over time: if you are a business or an individual, you may want to look into having a stable/lasting contact address, that will survive the inevitable collapse of facebook/whatsapp/instagram/… If you are old enough, your current email address probably existed before facebook. Why not your IM address?
And yes, I hear you, this is rather niche, but what got me there (and on XMPP in particular) is having been long-enough on the internet to become tired of the never-ending cycle of migrations from service to service. More and more people will have a similar experience as time goes, so this niche will only grow :)
If you are curious, you should give XMPP a shot, it’s equivalent to Signal in terms of encryption, but anyone can host their own. Signal is ideologically opposed to anyone but themselves being in control of your account, and because of that I don’t want to trust them.
I think you should give Trilium(Next) Notes a try:
it has the hierarchical notes structure that you are familiar with in obsidian
it has better ways of keeping things organized (attributes can be values or references, can be shared and inherited, which provides a flexible framework for having notes “types” as templates that can be extended, e.g. people vs. colleagues, businesses vs. companies, etc)
it has the concept of note hoisting (which lets you focus on a note and its sub-notes, so other projects/spaces don’t come in the way of autocomplete and placing references), and workspaces that builds further on top of that
it can be used standalone (local client/offline-only, like obsidian) but coupling it with a remote-server opens more interesting use-cases (synching, sharing notes with others by public URLs, one-user/multi-client editing) which gives the best of both worlds (local-first/online-first) and lets you access your personal notes on devices you don’t necessarily own (which obsidian doesn’t). The mobile app story isn’t great (it’s a PWA with limited offline capabilities at the moment), but isn’t worse than the alternatives either (I can’t really work and think long form on a handheld, no matter the editor experience, but perhaps that’s just me).