For me the main requirements are:
* Backed up to cloud
* Has a mobile app that is easy to make small changes (for example if I'm doing an oil change on my car I need to be able to pull out my phone and log it in the wiki easily)
* Simple file format like markdown so that you're not locked into something proprietary (no need for crazy formatting options like MSWord)
* Option to export data out as a backup
* Allow uploading arbitrary files like PDFs, images, receipts etc...
* Nice to have: support for inline tables of data with simple calculations/sorting
Trillium - https://triliumnotes.org/
Joplin - https://joplinapp.org
I personally use Flatnotes - https://github.com/Dullage/flatnotes with a connected git repository, but this does not meet your requirements.
I built it because Notion is way too slow. I loved Obsidian, but I wanted it to be multi-player so my whole team could use it. It is fast, open, and self-hostable.
It meets all the criteria you listed except the mobile app. Mobile app will be out next week. I'd happy to build any other features you need. Just let me know at k@hyperclast.com :-)
Has everything you want I think with plugins to do a ton more while still essentially being just Markdown.
My understanding is every device syncs its own full copy of everything?
So if you have a lot of images/PDFs, does your phone have to be able to hold everything at once?
So for many years it's been orgmode in emacs. Not exactly a wiki, but you can treat it as such. As they are "just text files", you can treat them as that and many things become simpler. Difficult to share with non-emacs users is probably the only downside.
- "mobile app" means "its web interface"
- "backed up" means to wherever you upload/sync your backups to
- No automagic table calculation support.
Also Logseq worth it.
It stores pages in a database, but you could export them in markdown. Web interface is mobile friendly, essentially an app.