Recs.
Updated
Zettlr is a cross-platform Electron-based Markdown editor that offers inline previews, citeproc support, easy exporting to all formats (even slideshows), syntax highlighting for many languages.
SpecsUpdate
Pros
Pro Focuses on writers
While many Markdown editors don't offer specific support for a certain type of workflow, or offer features for scientific workflows only, Zettlr offers features that help the writing process of journalists or researchers in the arts and humanities. It's a lot more text-focused than most editors.
Pro Almost perfect
This is the best option, still not perfect, there are some bugs like creating / editing tables and resizing images, but the PROS destroy the CONS. Easy quotes, WYSIWYM , attachments tab (supports attaching and opening links to any file), table of contents, TAGs, easy hyperlink between files (same as citations), export to many formats (like Word, HTML5, PDF)...
Pro It supports some really nice tag features and provides a unique heatmap search results feature
Cons
Con Tabbed window system can be confusing
It'd be nice to have more clear indications of where a note, open in a tab, corresponds to its place in the hierarchy. Also, tabs open or replace themselves automatically based on whether they've been changed or not. It can be difficult to keep track of which tab is going to replace itself the next time you click a note, especially when it opens many tabs.