My own summary of the best cross-platform text note apps
This is by no means the complete list of what is out there but I looked at what commonly comes up, and based it on what I was looking for. My own choice got skewed slightly by my work blocking Dropbox (if it were not for this I may well have preferred Laverna as my top choice).
Chiefly I was looking for:
1. Standalone text note taker which would sync between multiple devices.
2. Also needed a web login because my Windows work laptop won't allow me to install Windows apps.
3. Ideally able to share a link to a note.
4. Must be able to import and export my notes.
5. Preferably open source software.
6. I wanted some formatting eg. like markdown editing.
7. Tagging notes.
8. Insertion of a photo eg. of a whiteboard
In the end, I am staying with Simplenote (which I moved to about a month back) as it satisfies 90% of what I want at zero cost. Its backend not being open source is not my ideal, and the fact its major shortcoming for me is its lack of easy insertion of a photo/picture means I may well be re-evaluating this list in a few months again.
The short of it is:
1. Best features and support if you don't care for open source and don't want to ever import or export your notes (really?) = Microsoft OneNote.
2. Best features and support and you don't care for open source, but you need to import / export notes, and can live with syncing between only 2 devices = Evernote Free version.
3. Best featured open source notes editor but costs the most per annum = Standard Notes Premium.
4. Best free open source notes editor if Dropbox works fine for you = Laverna (actually its alternative RemoteStorage sync is not difficult to setup with 1GB free storage).
5. Best free open source note editor with own sync service and web login = Simeplenote.
6. Others to watch:
6.1 QOwnNotes - great to sync with a NextCloud/ownCloud server but you'll have to use the various clients as the NextCloud Note web interface is pretty useless.
6.2 Turtl - no web login but uses its own secure sync service and has good features in the various clients.
6.3 Joplin - looks very interesting with Evernote and Standard Notes import/export planned, iOS support planned. This is one I'll look at again in the future.
So I'll certainly be relooking at both Joplin and Laverna again in a few months.
See my summary of features at https://docs.google.com/spreadsheets/d/1gZJ8QrXxXKfOCyKDiS0xml9Fj0qkfZyQzeJ1ccdkpBI/edit?usp=sharing