When comparing GNOME To Do vs Taskwarrior, the Slant community recommends Taskwarrior for most people. In the question“What are the best productivity tools for Linux?” Taskwarrior is ranked 3rd while GNOME To Do is ranked 7th. The most important reason people chose Taskwarrior is:
The command line interface puts powerful filtering expressions, context, annotations, tags, due dates, reoccurrence, and user-defined-attributes totally in your hands. It’s fast and low friction.
Specs
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Pros
Pro In active development
They are working on grid and task planner like views.
Pro Deadlines
Setting deadlines is pretty easy.
Pro Priorities
You can give tasks priorities, and they are clearly defined.
Pro Syncs to some other task lists
I thinks it needs the GNOME settings manager to sync to Google and Microsoft's To Do lists.
Pro FOSS
That's good...

Pro Command line interface
The command line interface puts powerful filtering expressions, context, annotations, tags, due dates, reoccurrence, and user-defined-attributes totally in your hands. It’s fast and low friction.
Pro Extensible
Taskwarrior has many front-ends, services, extensions, hook scripts, and capsules available. Taskwarrior keeps a list of contributed tools on their site.
Pro Lightweight and fast
Taskwarrior is written in the speedy C++ language.
Pro Tasks stored in plain text files locally
Future-proof and easily integrated with version control system. You never lose access to your data.

Pro Sync across devices
When used in conjunction with the Taskserver, it can sync tasks (conflict-free) across your Taskwarrior devices. This includes integration with Mirakel.

Pro Supported internationally
It has UTF8 support and is translated into many languages.
Pro Customizability
Taskworrior allows you to define custom attributes and reports to your needs.
Pro Self-hosted Taskserver
You can be in full control of your data.
Cons
Con Linux only
No Windows or Mac support (though I guess you could make it work yourself, yay FOSS)
Con Command line interface
A command line interface is a arguably overly verbose, consequently tedious, way to interact with a To Do list.
