When comparing Texts vs Boostnote, the Slant community recommends Boostnote for most people. In the question“What are the best open source Markdown editors for UNIX-like systems?” Boostnote is ranked 16th while Texts is ranked 29th. The most important reason people chose Boostnote is:
Supports Windows, macOS and Linux.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Supports multiple Markdown dialects
Unfortunately, this is a global setting for save (it can open any dialect)

Pro Immediate Markdown rendering and preview
Texts immediately renders the formatted Markdown as you are typing it inside the text box. It's quite similar to a WYSIWYG editor.

Pro Imports and exports many formats
HTML, Word, TeX, PDF, ePUB, OPML.
Pro Works on Mac OS X and Windows
Pro Cross platform support
Supports Windows, macOS and Linux.
Pro Markdown support
Pro Free
Pro Open source
See here.
Pro Great for developers
Boostnote is great for developers looking to take programming notes with code snippets and such.
Pro Supports code snippets and syntax highlighting
Boostnote has the ability to store code snippets and comes with syntax highlighting out of the box, supporting many languages.
Pro Works offline
Boostnote doesn't require an internet connection to work. You can write notes offline and sync later.
Pro Global search, tag feature
Pro Comes with many themes
Boostnote comes with many themes out of the box, most of which are popular themes and color schemes for code editors: e.g. 3024, base16, solarized, tomorrow.
Pro vim/emacs key bindings available
Boostnote supports vim/emacs key bindings. If you're a developer familiar with either of them, navigation should be easy to pick up.
Cons
Con Overwrites standard Markdown
Editing a preexisting Markdown document overwrites standard markup in it (for example, interpreting headings marked with leading "#"s and rewriting them with a trailing underscore line), adds extra blank lines between all paragraphs, and adds extra spaces at the head of unordered-list items.
Con Spell checking is not activated by default
There's a built-in spell checker which is not activated by default and is quite hidden.
Con Limited choice of built-in themes
You can download the CSS for these themes and create your own, but would be nice to have more flavors (e.g. GitHub)
Con No word count in older versions
Word count is present in Texts 0.21, at least.
Con Some of the features are not consistent
Con Must use third-party service for sync-ing (Dropbox, etc.)
Boostnote does not have sync-ing capabilities and relies on third-party services to fulfil notes storage. There are additional steps involved to set this up.
Con Can't work in "real" offline mode
Con Very poor syncing
Data loss may occur on syncing.
