When comparing Byword 2 vs Quiver, the Slant community recommends Byword 2 for most people. In the question“What are the best Markdown editors for OS X?” Byword 2 is ranked 2nd while Quiver is ranked 16th. The most important reason people chose Byword 2 is:
Byword de-emphasizes the syntax itself while emphasizing its effects. It appropriately adds style, like italic and bold, to text that's designated by markdown and dims the syntax so it does not get in the way of comprehension. Additionally, there are commonly used hotkeys (⌘b, ⌘i, etc) that can be used to apply style without having to know the syntax or having to type it out each time.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great Markdown support without being intrusive
Byword de-emphasizes the syntax itself while emphasizing its effects. It appropriately adds style, like italic and bold, to text that's designated by markdown and dims the syntax so it does not get in the way of comprehension. Additionally, there are commonly used hotkeys (⌘b, ⌘i, etc) that can be used to apply style without having to know the syntax or having to type it out each time.
Pro Available for all Apple devices
Byword is available on a Mac, an iPhone and iPad.
Pro Extremely simple
Byword is as simple as Markdown editors can get. Even though Markdown itself is not hard, Byword offers assistance to make it even easier with very little configuration required.
The UI is minimalistic and un-intrusive, the syntax auto-completion is excellent, and there are multiple small but helpful features that make writing Markdown with Byword a breeze.
Pro Syncs using iCloud and Dropbox
Documents can be synced using iCloud or Dropbox from within the editor for use across all devices.
Pro Direct publishing to web platforms
Byword allows users to publish their markdown files directly to web platforms such as Wordpress, Tumblr, Blogger and even Evernote.
Pro Word count support
Has a built-in word counter.
Pro Multiple export options
You can export to HTML, PDF, RTF.
Pro A dark theme is available
For people who enjoy working during the night, there's a dark theme available that reduces strain on the eyes.
Pro Includes features that speed up writing
For example, while authoring a bulleted list hitting return automatically prepares a new bulleted line.
Pro Live update support
Byword has a "Preview Markdown" option where it does exactly what it promises. It immediately compiles and displays the rendered Markdown file, making it easy for the user to understand how they are actually formatting their document.
Pro Supports Multimarkdown
Byword supports all the table types in Multimarkdown including table captions. MathJax support is added via metadata at the beginning of file was well as support for various diagrams. Table of Contents is also supported.

Pro Supports iCloud Drive and Handoff
One of the few (well, Ok, only for far) that has been updated for Yosemite features. Jan 2015.
Pro Updated frequently
Byword gets frequent updates which add new features or fix existing bugs.
Pro Has more features than just a simple Markdown editor
Quiver is a notebook and note-taking app akin to Evernote which happens to also be able to edit Markdown files. As such, it has a lot of useful features such as: image support, file attachments, web content support and more.
Pro Supports code highlighting
Has syntax highlighting for more than 120 programming languages.
Pro Notes can be linked to each-other
Quiver notes have unique links that can be copied and pasted into other notes to gain quick access between them.
Pro Live preview
Quiver has live preview for both Markdown and LaTeX. This helps users to better understand the way they are formatting their files.
Pro Cloud syncing
Dropbox, iCloud Drive, Google Drive, or any other file-based cloud services.

Pro Supports vi keybindings
For people used to vi keybindings, Quiver can be set up to work with them.
Pro Combination of different types of writing in one note
The most outstanding thing for me. Use HTML line breaks while writing MD text.
Also, unlike most hybrid editors like Bear, it supports instant image sizing and respective preview.
Cons
Con No support for code blocks
I need my markdown editor to support code blocks like
def foo(bar, baz):
qux()
This one does not.
Con Publishing requires additional in-app purchase
The feature to publish Markdown files to web services costs an additional $5 of in-app purchase.
Con Expensive
Con Limited customizability
One of the things that makes Byword so easy to use is the fact that it needs very little setup and option-tweaking. However, that severely limits the ability to customize the editor itself. For example, there are only two themes available, a light one and a dark one.
Con You can't edit specific files, they must be in your notebook
Con No iOS apps for editing, only a viewer available
I'd LOVE to edit and create quiver notes on my iPad!
Con The line in focus shows a border around it which is distracting
The line in focus in the editor shows a rounded rectangular border around it, which is unappealing and distracting.
Con Much more than a simple Markdown editor
Since it's more like a note-taking app (and a note-taking app built for developers) than a Markdown editor, it may be a little excessive to use it only for its Markdown editing features.
