When comparing Emacs Org-mode vs Sandglaz, the Slant community recommends Emacs Org-mode for most people. In the question“What are the best cross-platform task apps?” Emacs Org-mode is ranked 3rd while Sandglaz is ranked 45th. The most important reason people chose Emacs Org-mode is:
This app's flexibility is based on its minimalist approach, giving the user near-infinite freedom.
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 Simple interface, great for milestone sprints
The interface is built around the concept of "infinity grids" where tasks are placed into time-based milestone periods. Any non-completed tasks from the current milestone automatically move to the next milestone. As such Sandglaz is best suited for teams that plan projects and tasks in milestone sprints.
The interface consists of columns of tasks organized in either days or weeks with a slide-out panel for accessing settings, search, notifications and navigating projects. Expanding a task gives access to adding subtasks, notes, attachments, comments, setting due dates, etc. Overall the interface is very utilitarian in execution with only the bare minimum of functionality taking up the space at any given time.
Tasks are assigned with @username. Each project can be shared with its own team of collaborators. And hashtags are used for categories.
Pro Automatic task management
Uncompleted tasks move to the next day automatically.
Pro Very easy to collaborate with team members
You can assign tasks with @username and communicate about your collaborative to-dos right within the context of the tasks. You can also share each project with its own team of collaborators.
Pro Advanced recurring tasks functionality
Sandglaz allows users to create really smart recurring tasks – everything from “weekly” to “on the fourth Saturday of the month.”
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 No native apps
It can only be accessed using the web client – there are no native apps for desktop or mobile.
