When comparing marker vs Zettlr, the Slant community recommends Zettlr for most people. In the question“What is the best WYSIWYG Markdown editor?” Zettlr is ranked 9th while marker is ranked 17th. The most important reason people chose Zettlr is:
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.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free and Open Source
Pro Themes
Pro Low Resources required
Pro Support Math
Pro Single/Dual Pane view
Pro Almost every feature Typora has
Pro support Document classes
Pro Beamer/presentation mode (class: beamer)
Pro Abstract sections
Pro Support Table of Contents
Pro External document inclusion
Pro Equations, figures, table and listings with reference id and caption
Pro Internal references
Pro Extra scientific syntax of SciDwon wiki
Pro TeX math rendering with KaTeX and MathJax
Pro Support for mermaid diagrams
Pro Support for charter for plot
Pro Syntax highlighting for code blocks with highlight.js
Pro Integrated sketch editor
Pro Flexible export options with pandoc
Pro Support YAML headers
Pro Scidown support with HTML and LaTeX conversion
Pro Wide Variety of Export options
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 Citation support
While it supports a diverse range of syntax (chart, easy image insert, etc.) found in other editors, the great citation support made it possible to write real articles. Citation from Zotero and Mendeley can be inserted easily which is a huge plus.
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 Renders math in-place through KaTex
Cons
Con Obtrusive, like someone WITH CAPS LOCK ON
Too loud, too much going on, and definitely an in-your-face sort of feeling.