When comparing Emacs Org-mode vs Boostnote, the Slant community recommends Boostnote for most people. In the question“What is the best note taking app for Mac?” Boostnote is ranked 4th while Emacs Org-mode is ranked 18th. The most important reason people chose Boostnote is:
Supports Windows, macOS and Linux.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Ultimate flexibility
This app's flexibility is based on its minimalist approach, giving the user near-infinite freedom.
Pro Absolutely free
Emacs with Org-mode is free as in beer and free as in speech – that is, it costs nothing and it’s totally open source.

Pro Files are usable anywhere at anytime
Users are not tied to one service provider, program, platform, or database engine.

Pro Incredibly extensible
There are many plug-ins for Org-mode, including Org-habits and Org-notify. If Org-mode lacks some piece of functionality, it is very easy to add it.
Pro Agenda views
Pro Excellent unofficial Android app (orgzly)

Pro Offline support
Pro Efficient features for deadline organization
Pro Supports plaintext spreadsheets
Pro There are a lot of extensions, for exporting to html, bootstrap, js-reveal and much more
Pro Quickly add rich text
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 Unintuitive user interface
The key combinations are unintuitive and difficult to remember. This is probably because there are a lot of hidden "modes" depending on where the cursor is. Actions aren't paired with reversing actions like in other todo apps. For example, hitting shift-tab does NOT reverse the effect of hitting tab.


Con Android app isn't very good
There are several user-created apps for Android, but none seem to offer the same level of functionality as other to-do apps.
Con Not really cross platform
Although it is possible to get a lot of it working, no all in one, sync included, out of the box solution is available for mobile devices.
Con By default, a hard-to-read display
The default way of writing an outline or checklist creates a very messy wall of text that's difficult to read with no vertical spacing. You can manually add vertical spacing, but the Org operations don't preserve it. There are pretty-display modes, but you need to remember how to enable them, etc. etc.
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.
