When comparing Things vs Momentum, the Slant community recommends Things for most people. In the question“What are the best GTD apps?” Things is ranked 4th while Momentum is ranked 12th. The most important reason people chose Things is:
You can set it up so that Siri can voice dictate your tasks, which is pretty handy when you're really busy or you need to drive a lot.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great for people who needs their hands free because it can work well with Siri
You can set it up so that Siri can voice dictate your tasks, which is pretty handy when you're really busy or you need to drive a lot.
Pro Has a cloud service that makes it easy to sync on devices like your phone and computer
Pro Has a simple layout that's easy to understand and use
Pro Specifically designed for GTD
Pro Automated Next Steps
Next steps have a separate view. Tasks can be updated sequentially or parallel.
Pro Projects and Tasks can be endlessly nested
You can nest multiple projects with tasks, there is no limit.
Pro Has an offline mode
No permanent internet connection needed.
Pro Cross-platform
Web-based, progressive-web-app (PWA).
Pro Realtime synch
Data instantly updates on all devices.
Pro Clean design
Lots of space helps focus on the tasks.
Cons
Con Not collaborative
Would be nice to share tasks with wife.
Con Beta interface is confusing for first-timers
The interface is very opinionated (this is a good thing). But it is not obvious how to map user's own GTD variant onto the one the author has in mind. Maybe after it is in production, there will be better on-boarding.