A couple of years ago Roam Research was trending, I read some articles and reviews about it and I liked the concepts it introduced. I looked for a free, open source self-hosted cross-platform alternative to Roam and found Trilium.
Its native on Windows, Mac, and Linux, while it doesn't have any Native Mobile apps, the webapp works on great on mobile and can be installed to your phone launcher as a PWA.
It does everything I want, and I use it a lot. A bunch of my colleagues have been recently moving from Evernote or Notable, over to Obsidian, and I understand Obsidian is the new hot thing, but I think I'll stick with Trilium.
My advice would be to try out a bunch. Note taking is surprisingly nuanced and personal preferences play a major role. Try each one for a week or two, and see which best matches your workflow and your requirements.
I also useTrilium but I have to say that the mobile experience is pretty poor. You loose the ability to add labels and most of the desktop features are stripped away. If all you need is to simple read and write, then the mobile web app may suffice. There is also a bug where many android keyboards cause typed characters to duplicate (a ckeditor bug)
I'm still sticking with Trilium because the desktop app is super. I'm definitely looking forward to a mobile app at some point (its bound to be developed by someone!)
I agree with that, mostly. However I find I don't really ever need to add or edit content on mobile. I only use the web app on mobile to lookup something when my laptop isn't at hand. There is the official Trilium Sender app for Android that allows you to forward text, pictures, links, etc from your device to your Trilium server, then you organise the content when you get back to your laptop. I find that fills any gaps in functionality. I hate brain dumping or editing long or complex paragraphs of text on my mobile anyway.