Byword 4+

Byword is one of the original markdown editors for the mac and iphone/ipad and hasn't lost any of its original charm in all the years I've been using it. It allows me to write markdown or rich text and can navigate to files across my Mac or iOS device.

With Byword simplicity and distraction-free meets pure writing with the aim of Byword being to keep everything really simple and straighforward. It just leaves nothing in the way of the writer and the written word, nothing stopping that pure flow of thought onto the screen. I've tried most of these type editors, such as iA Writer and Paper, both of which have their own strengths but I always come back to this lean, clean, fast editor which is only 6.5mb in size.

If you write you should try this. 5 Stars!

2021 Update
I still like Byword and continue to use it for focussed writing when words are more important than appearance. It is still my favourite pure writing app.
Byword is fast, the workspace uncluttered and dictation works really well. When I need to concentrate on what I am writing I have only Byword open and use a large font size that can be read easily and quickly.
However, over the last five years, I have used Drafts for quick notes that can be saved easily to other apps or file locations. I also use iA Writer when I need Markdown formats I cannot always remember, to see the preview in split screen, and for style checking.
I quite often write the main text in Byword to stay focussed, then format it and add images in iA Writer.
A unique and useful feature of Byword is that it is an add-in to DEVONThink and a great way to edit notes.

2016 Review
I use Byword on my Mac and my IPhone, with iCloud synchronisation.
I do not use all its features, but still find it an essential tool.
I use it to capture notes quickly and without fuss. I can then format them later or publish them to Evernote or other apps. I am increasingly saving copies of important files in plain text to time proof them against “upgrades" to word processors that can make older files unreadable.
Byword is a simple but very effective application that I use every day.

Cheesy part: Im a longtime Byword user and love the cleanliness of this app, and the way it has evolved over time blah blah blah…

Useful part: It has excellent Markdown (including tables!) and HTML support. Only one slight issue that I have noticed thus far: when you link a photo from and iOS device’s photo app, then come to open the same doc on the Mac, I often encounter fidelity issues, mostly to do with orientation. Small bug.

AOB: This app has been in existence for a few years (5?), with regular updates.