When comparing Texts vs Textnut, the Slant community recommends Texts for most people. In the question“What are the best Markdown editors for OS X?” Texts is ranked 20th while Textnut is ranked 26th. The most important reason people chose Texts is:
Unfortunately, this is a global setting for save (it can open any dialect)
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 Can automatically convert Markdown to rich text
TextNut has two modes that it can switch between on-the-fly - Markdown and rich text editing mode. In rich text editing mode Markdown syntax is automatically converted to rich text. For example, typing ***bold***
will automatically convert it to bold. In Markdown mode syntax will be kept (with chosen styling applied).
Pro Advanced yet easy way to add images
Images can be added by writing a curly brace ({
) anywhere in the text and a popup will appear that will allow dragging and dropping the image in as well as customize the parameters without having to remember the proper syntax.
Pro Effectively does WYSIWYG editing
Pro Easy document management
Drag and Drop tree structure document management, powerful and flexible.
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 Rich text editing mode has incomplete Markdown support
Some Markdown elements don't convert to rich text in rich text editing mode. For example, for emphasis only *
will convert, _
will be left as is.
