I think it's worth looking at the competition to see how they do things.
Quiver (free trial, $9.99 full)
_The Programmer's Notebook_
Thoughts
Closed source, semi-abandoned, iOS app not very useful
QOwnNotes (free full)
_Plain-text file notepad with markdown support and ownCloud integration_
Notes
Average.
Ulysses (subscription)
_The Ultimate Writing App for Mac, iPad and iPhone_
Notes
Good, apart from subscription pricing.
Agenda (free, paid features)
Agenda is a date-focused note taking app for both planning and documenting your projects.
Mweb
Pro Markdown writing, note taking and static blog generator App
Before FSNotes, I looked far and wide and couldn't find anything that supported my three essential features:
Also I really dislike monthly/yearly subscription pricing.
In other words I wanted nvALT... except that I want it to actually run properly in 2018 😄 So as far as I have seen, FSNotes is absolutely unique and I am stoked it exists. Still, I agree, worth seeing what niceties could be "borrowed" from other apps.
The note app that's included with macOS Sierra is actually quite nice, but it stores the notes in just a few files deep in the file system. Plus, it's a bit slow on my antique mac mini. FSNotes is perfect for me.
Came across this one tonight...
MemPad
http://www.horstmuc.de/wmem.htm
I really like the nested directory tree/list because I use nested folders in my notes

Sorry, I'm struggling to see anything in that screenshot... 100% of my attention is on that fabulous Windows UI 🤣
Keep It (free to try, various pricing options)
http://reinventedsoftware.com/keepit/
– macOS version is buy _or_ subscribe
Apparently this has been in development under a few different names for 14 years (Keep It Together, 2004–; Together, 2007–; Keep It, 2017–).

I think FSNotes is, in many areas, ahead of all those functionally (I read each one's promo spiel but didn't download and try them all — and of course most have their own specific strengths).
However, IMO many of them do have a very nice, polished UI, which really I think they need, to set themselves apart. I think FSNotes' UI will continue to improve but primarily its features set it apart, for me.
Caret, Typora - Electron apps, so no thanks
iA Writer - this indeed very nice
Letterspace - discontinued? at least not available in the UK App Store and developer absent since 2016
Falcon - quite nice
For me one of the main plus points of FSNote is the active and involved development. And also the easy access to the notes file storage. I'd like to see how easy that is in Falcon, and to a lesser degree Letterpress.
I had never heard of Falcon, but it's a nice looking app. However, it was last updated in March 2017, which is not encouraging. I do like the app's use of the term Notebook, for what FSNotes calls a storage area.
https://zettelkasten.de/the-archive/
support forum: http://forum.zettelkasten.de
I really like the use of a long reverse date string ("zettel ID", eg. 201802121037) to order/timestamp notes and make cross-reference easier.

Drafts 5
https://getdrafts.com/gettingstarted/overview
Extensive feature set with a focus on sharing the text you write.
iOS for now, macOS in short term future.

currently free, possibly abandoned?
Simple
Surprisingly Adept
Let Me Add
Mooted as Electron app with database storage. Abandoned by developer.
Here's another one: https://standardnotes.org
It's open source and often the default suggestion you'll get in privacy-conscious groups
Can't remember why I stopped using it but there must have been something basic that caused friction with me because even though it looks polished I deleted it after 5 minutes
I tried many of the apps suggested above, and loads more I can't all remember.
In the end I gave up and settled for a combination of:
So I'm really excited about FSNotes and hope this will finally allow me to combine things in a single place without getting locked in
The successor to nvALT has been announced.
Codename: nvUltra
https://brettterpstra.com/2019/04/10/codename-nvultra/
This app works a lot like nvALT (and Notational Velocity, naturally). You pop it up and start typing. Search or create a note in seconds. It has blazing fast and accurate full-text search, the ability to find related notes based on content, and very complete Markdown editing tools (complete with syntax highlighting and theme editing). The biggest difference is that it works with multiple folders and sub-folders. You pick a folder, it indexes it, and you can use it just like nvALT. But then you can open another folder, or create a new one and start editing. It allows you to create folders anywhere, maybe one on Dropbox or iCloud Drive that’s shared, one on an encrypted disk that’s private, one for work, one for home, one for every writing project. You’re not limited to tags (though you can search by and sync with macOS tags within the app), and you can sort your notes into subfolders as well.
Interesting points:
nvUltra: unlike nvALT, it has no RTF and no intention to support it. Just another markdown editor from my point of view.
Most helpful comment
Before FSNotes, I looked far and wide and couldn't find anything that supported my three essential features:
Also I really dislike monthly/yearly subscription pricing.
In other words I wanted nvALT... except that I want it to actually run properly in 2018 😄 So as far as I have seen, FSNotes is absolutely unique and I am stoked it exists. Still, I agree, worth seeing what niceties could be "borrowed" from other apps.