When comparing Casual vs Priority Matrix, the Slant community recommends Priority Matrix for most people. In the question“What are the best cross-platform task apps?” Priority Matrix is ranked 47th while Casual is ranked 67th. The most important reason people chose Priority Matrix is:
Priority Matrix helps me focus on what's truly important on my todo list, so I can work more efficiently.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Tracks task dependencies using a graph
Pro Great to-do templates
Every to-do list & project can be saved as an amazing template that you can re-use in the future.
Pro Offers a high-level overview of projects
The workflow with dependencies shows where the things are at a glance. No more frustrations of how your project is going and who is doing what.
Pro Sync deadlines to Google Calendar
To-do items can be integrated with your day-to-day schedule using Google Calendar.
Pro Visual way of organizing your work
The workflow includes dependencies and shows you where things are at a glance.
Pro Helps prioritize, rather than simply listing tasks
Priority Matrix helps me focus on what's truly important on my todo list, so I can work more efficiently.
Pro Super easy to share / delegate tasks
All I have to do is press a button, rather than drafting a whole email to one of my co-workers.
Pro Solid methodology
The software implements time proven methodologies; not just a to-do list.
Pro Lots of different views
Priority Matrix makes it really easy to see your task list in different ways: You can see it in the quadrant view, calendar view, a filterable list, and also a Gantt Chart if you have the business license.
Full disclosure: Originally posted by an Appfluence Intern (who was equally impressed with the software's layout and functionality before working there)
Cons

Con Price
At its cheapest level, Casual is $9 per month for two users and two GB of storage. The trial period is short and there is no free version.
Con Expensive
Used to be free, is now $12+ a month.
