When comparing Texts vs MacDown, the Slant community recommends MacDown for most people. In the question“What are the best Markdown editors for OS X?” MacDown is ranked 5th while Texts is ranked 20th. 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 Supports multiple Markdown dialects
Unfortunately, this is a global setting for save (it can open any dialect)

Pro Immediate Markdown rendering and preview
Texts immediately renders the formatted Markdown as you are typing it inside the text box. It's quite similar to a WYSIWYG editor.

Pro Imports and exports many formats
HTML, Word, TeX, PDF, ePUB, OPML.
Pro Works on Mac OS X and Windows

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 Overwrites standard Markdown
Editing a preexisting Markdown document overwrites standard markup in it (for example, interpreting headings marked with leading "#"s and rewriting them with a trailing underscore line), adds extra blank lines between all paragraphs, and adds extra spaces at the head of unordered-list items.
Con Spell checking is not activated by default
There's a built-in spell checker which is not activated by default and is quite hidden.
Con Limited choice of built-in themes
You can download the CSS for these themes and create your own, but would be nice to have more flavors (e.g. GitHub)
Con No word count in older versions
Word count is present in Texts 0.21, at least.
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.
