When comparing MarkdownPad vs Write!, the Slant community recommends Write! for most people. In the question“What are the best open source Markdown editors for UNIX-like systems?” Write! is ranked 10th while MarkdownPad is ranked 36th. The most important reason people chose Write! is:
Write! has tabs at the top and a tree view on the left that allows quickly switching between different files.
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Pros
Pro Allows customizing output
A custom CSS can be added to the rendered HTML to change the preview and output.

Pro Real-time HTML Preview
MarkdownPad is split in two panes. One pane is used for writing Markdown, the other shows the rendered HTML as it's written.
Pro Allows easily switching between working on multiple files
Write! has tabs at the top and a tree view on the left that allows quickly switching between different files.
Pro Interface doesn't get in the way of work
The interface is minimal, when it's windowed there are no buttons or toolbars, so it doesn't distract from work. When it's in fullscreen, there's just text, no interface at all.
Pro Endless undo/redo
Write! uses a file format that saves all versions of a document. Meaning even if the app is closed and then opened up again, Write! can restore any previous version of the document.
Pro Can double as a to-do list app
Write! has a to-do list mode that allows creating lists of items in groups (tabs) that can be ticked off when completed.
Pro Picks up where you left off next time you start the app
Write! saves the state that it's in when closed and restores that state when opened. You can pick up working on documents in the exact same place you left off - same documents open, same cursor placement, etc.
Cons

Con Many features are disabled in the free version
Free version lacks features like auto-save, PDF export, Markdown tables among many others and can't be used commercially.
Con Abandoned project
Nothing from author since 03/15. Pro version preview pane crashes, no fix has been offered. See user forums.
Con Preview window crashes / does not update
Con You need to login to the App, and it reconnects to their server
There is no offline use.
Con Not free
There are free markdown editors for windows, this is not one of them.
Con Needs better folder document management like Ulysses
Con Needs nested folders
Con Bad MarkDown features
Not worth $20, the markdown editor sucks.
Con In beta
The app is not yet complete. A lot of the promised functionality is not yet implemented.
