When comparing MarkdownPad vs ResophNotes, the Slant community recommends ResophNotes for most people. In the question“What are the best open source Markdown editors for UNIX-like systems?” ResophNotes is ranked 11th while MarkdownPad is ranked 36th. The most important reason people chose ResophNotes is:
It's possible to put the app on an external device and run on another Windows device without having to install it.
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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 Portable
It's possible to put the app on an external device and run on another Windows device without having to install it.
Pro Notes can be organized via tags
Notes can have tags associated with them allowing you to group notes together based on whatever criteria you choose. Now you can, for example, look at all notes related to a specific event, a specific project or a specific group of people.
Pro Free
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 Can't configure hotkeys
There's no way to change keyboard shortcuts.
