When comparing Brackets vs MacDown, the Slant community recommends MacDown for most people. In the question“What are the best developer tools for Mac OSX?” MacDown is ranked 4th while Brackets is ranked 27th. The most important reason people chose MacDown is:
MacDown is a free and open source editor influenced by [Mou](http://25.io/mou/). It's released under the MIT license.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Built-in browser live-updating
Brackets will automatically refresh the browser and load the latest saved version of a file open in the browser. This works with php as well. Editing a css will even highlight the tag that's currently being worked on. However, it only works with Chrome.
Pro Lightweight
Brackets is easy on memory usage and it starts up quickly.
Pro Free, open source and cross-platform
Brackets is entirely free and open source.
Pro Built-in extension manager
The functionality of Brackets can be extended via a simple-to-use extension manager. The extension manager also has a considerable number of extensions and themes.
Pro Can style a tag without switching over to the stylesheet
A feature called "Quick Edit" allows the user to select a tag in (a html file, for example) and edit the associated style without switching over to the css document. It also supports SASS and LESS pre-processors.
Pro Actively developed
Brackets is being actively maintained and developed.
Pro Popup previews
Hovering over colors hex codes or image paths will pop up previews of corresponding colors and images.
Pro Drag and drop support
Brackets supports drag and drop of text, as well as multi / rectangular selection.

Pro Can be hacked by any front-end developer
The editor is built using html, css, and javascript, making it extendable by any front-end developer.
Pro Multi-line (multi-query) editing
You can have your cursor independently on multiple lines and so creating templates and/or editing multiple things at once is really fast and easy.
Pro Vim mode
Vim-style editing is already built in the text editor.

Pro Support for Adobe PSD content
A default extension allows for the extraction of PSD resources, such as images and styles. There's good integration for placing extracted resources into source.

Pro Free and open source
MacDown is a free and open source editor influenced by Mou. It's released under the MIT license.

Pro Real-time split-screen preview
MacDown's main view is split into two panels. The user types on the left and the Markdown is rendered on the fly in the right panel. This helps users to better understand the way they are formatting their document.
Pro Markdown previews can be customized with CSS
You can use a CSS file to customize the rendered output and the file preview you are working on will display the rendered Markdown with the custom CSS styling on top.

Pro Supports syntax highlighting in fenced code blocks
MacDown has syntax highlighting support for various languages when writing code in fenced code blocks.
Pro Good auto-completion
MacDown has a good built-in auto-completion engine for Markdown symbols.

Pro Support for GFM
Pro Ideal for day-to-day programmers' work and MarkDown novices alike
Using MacDown for the notorious README.md use case gets you going without reading any manual or requiring any configuration values. Think of it as a sort of TextEdit for MarkDown files. Thus its shortcomings - neither powerful nor versatile - turn out to be a PRO for novices trying to jump on the MarkDown bandwagon. Open its help and you'll immediately find yourself editing the MacDown's MarkDown help file, a MarkDown primer with some MacDown menus and configuration added.
Pro Linking between pages
Unlike a few other editors, MacDown lets you link between markdown pages.
Pro Tool bar with most used markdown shortcuts
This is especially useful for Markdown novices
Cons
Con Still missing some elementary text editor commands
Some gaps have to be filled by plugins, while these features should be built in.
For example:
- Jump to matching brace (bracket / parenthesis);
- Gutter selection of lines;
- Recall previous searches / replacements;
- Autofill of search field with text under caret (text has to be selected);
- Show whitespace / end of lines / indentation guides / right margin;
- Selection to upper / lower case;
and some more.
Con Problematic updater
Though the website says there is an update available, the updater in Brackets may give you an error, resulting in you having to download updates manually.

Con Slow
Con Supports only web languages by default <but>
Brackets is built for web development and that's where it excels at out of the box. Other languages that have a CodeMirror mode can be added as well.
<and language support plugins can be added>
Con Not very versatile
MacDown is not very powerful or versatile. It's not customizable or extendable. This is what makes it so simple, but it's not for people who want more from their tools.
Con Frequently fails to update the display and/or flat out hangs
Must often restart MacDown.
Con The Markdown preview is rather heavy on the CPU
The Markdown preview needs a lot of resources to keep rendering on-the-fly after each keystroke. A single keystroke in the editor panel may trigger up to 5 seconds of max-CPU usage.
