When comparing RemindersPro vs Momentum, the Slant community recommends Momentum for most people. In the question“What are the best cross-platform task apps?” Momentum is ranked 34th while RemindersPro is ranked 73rd.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro No sign-up required
No need to sign up on some external website. Works out of the box.
Pro Works with iOS reminders app as well
Not proprietary, easy to switch back to the built-in iOS reminders.
Pro Supports workflows
It has workflows to automatically move and reprioritize reminders. And these changes will even be reflected in your iOS Reminders app. E.g. If you have a "Call" list and you say to Siri "Remind me to call mom" then it will automatically move it in there. Or you can set up a rule to move reminders containing your boss's name into your "Work" folder.
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 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.