I’ve used iA Writer. It’s what you’d expect.
The issue I find with many Markdown authoring apps is that there’s very little they can offer that adds any real value over any other Markdown authoring app. The more features they pack in, the more likely they are to start inventing new markup that breaks the portability of your documents, and the more likely they are to not quite meet your needs. It’s very easy to lose sight of the fact that the point of Markdown is that it’s legible in a plain ol’ ordinary text editor.
So far I greatly admire the developers of Obsidian for making it a priority to not redefine or create new markup for the sake of adding niche features to Obsidian. The Obsidian link style is pragmatic, but not required.
Day to day, I tend not to use any fancy piece of software at all, I just SSH into my home server and fire up a console text editor, or more often several at once. Since I do most of my writing on my iPad my most used tool is Blink, a terminal with SSH and Mosh clients baked in. For publishing I use a Bash script, cleverly named publi.sh, which utilizes pandoc to convert entire directory structures into websites. With this setup I can create and publish new notes with a simple iOS shortcut, or by talking to Siri while I’m doing something else entirely.
At home I really do enjoy using Obsidian, but it’s still not as flexible as my current setup. Once the export to standard Markdown feature is available I can see myself using it more, since then my publi.sh script will be able to handle Obsidian vaults without reinventing the wheel. In the future, a mobile app would be great, and the ability to run Obsidian as a web application, such as VS Code Server, would be killer.