Submitted in response to the link to Joplin yesterday. Zim can work with any cloud storage that you can save directly to (ie dropbox) and supports most wiki-like things. I've been using it for about 7 years and have extensive notes in it. It's quite good.
If you can get the hang of using templates in Zim, it can be used for more than just a wiki. One can create HTML pages or use them with a server side language like Python or PHP.
I have been using it as a CMS on and off to create websites and it just works. Really extensible piece of desktop software.