When comparing MultiMarkdown Composer vs Stylo, the Slant community recommends MultiMarkdown Composer for most people. In the question“What are the best Markdown editors for OS X?” MultiMarkdown Composer is ranked 12th while Stylo is ranked 43rd. The most important reason people chose MultiMarkdown Composer is:
Not many popular Markdown editors support MultiMarkdown syntax.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Multimarkdown support
Not many popular Markdown editors support MultiMarkdown syntax.
Pro Multiple export options
You can export to HTML, PDF, LaTeX, RTF, OpenOffice, Microsoft Word, ePub, OPML.
Pro Table of Contents support
Generates a table of contents based on the headers in the Markdown file being worked on.
Pro Support for elastic tabstops
Elastic tabstops are used to align text automatically during writing. When there's a change in the text, MultiMarkdown Composer automatically aligns all lines both on the beginning and end of them.
Pro CriticMarkup support

Pro Optional synchronized scrolling
Hold a key down and get synchronized scrolling.
Pro Fast syntax highlighting
Pro Highly customizable
Pro Counts words, characters, lines
Pro Can show invisible characters
Pro Flexible styling using CSS
Markdown source styling is really flexible because the App relies on CSS.
Pro CSS style definitions editable inside the editor
There is no need for complicated theme manipulation steps to create a style, everything is right in the editor along with the Markdown source.
Pro CommonMark support
CommonMark Markdown standard got a lot of traction lately and it's good to use an editor that conforms to it.
Cons

Con Table of contents gets out of sync sometimes
If you keep the auto-generated table of contents open while you work it gets out of sync, meaning items in the table of contents (at the end) disappear until you restart the program.
Con The way the preview shows images is inconsistent
The preview is a bit inconsistent with images. Sometimes it shows the image correctly, sometimes it shows a blue question mark.
Con Pretty new
