Atom: https://github.com/atom/markdown-preview https://github.com/atom/language-gfm

and

Gitbook editor: https://github.com/GitbookIO/editor

Previously Marked (http://marked2app.com), sometimes Vim, more often iA Writer because it blends markdown syntax with rudimentary formatting, and is well suited to editing text. (http://ia.net/blog/ia-writer-for-mac/)

I use sublime text 3 with following 2 plugins - Markdown Preview, for previewing in browser - Markdown Editing, great editing environment

I don't prefer online editors as don't like to see the live preview while I'm typing. But here's a good one dillinger

I can second the Sublime Text recommendation and add MarkdownPad (http://markdownpad.com/) for Windows.

I tried using Sublime text 3 for markdown but there was no significant syntax highlighting.

Sublime Text 2/3. Great for code and markdown. I used to use Brackets because of the live preview for web development, but the simplicity and design (I use the "spacegrey" theme) makes it a pleasure to use. It has an unlimited trial or you pay $60, I believe.

I use LightPaper and like it a lot. The features I like most are side by side preview and editor window and export to PDF and HTML. Previously I was using Mou but gave up after stability issues.

I can also vouch for LightPaper. The live preview is useful to check whether I messed up with my Markdown formatting somewhere.

http://clockworkengine.com/lightpaper-mac/

If I need something like live previews of my work as I am writing it, I just use light-table with the appropriate plugins.

Otherwise, any old text editor works for me.

Use <whatever> for editing and Marked for live preview:

http://marked2app.com/

I've used FoldingText:

http://www.foldingtext.com

I like Mou

http://mouapp.com/

Sublime Text with the Markdown Extended plugin, or Vim, whichever is closer at hand.

Isn't the entire point of Markdown that you don't need a special editor for it?

Yes, but that doesn't mean some editors aren't more interesting or functional than others.

if I want a live preview then I use http://stackedit.io. Most of the times I just use ST+Markdown plugins already mentioned here.

Haroopad is rather good on OSX. Give it a try.

Vim.

Exactly. Markdown, for me, is text, which you can read in the raw, and transform if you like.

Agreed. Here I treat nearly all text as text and edit in vim. That's why I like how simple and readable Markdown is.

Having a different editor for different text documents seems redundant to me. However I'll admit my two exceptions are using Xamarin for C# and ADT for Android apps.

Macdown is ok