When comparing Casual vs WeDo, the Slant community recommends WeDo for most people. In the question“What are the best cross-platform task apps?” WeDo is ranked 41st while Casual is ranked 67th. The most important reason people chose WeDo is:
Has versions for Android, Web, and iOS.
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 Cross-platform
Has versions for Android, Web, and iOS.
Pro Supports file attachments
You can attach files to each task.
Pro Great user support
It is a new app, but they have a very good interface so the users can send their suggestions to improve the app.
Pro Users can add recurrent tasks
It allows users to set recurrent tasks.
Pro Supports subtasks
You can add subtasks to any task.
Pro Allows users to assign tasks to other users
It allows you to assign tasks to other person. If he/she does not use WeDo, it sends an invitation.
Pro Clean interface
Pro Free
At least for a while.
Pro Supports groups
You can add groups, and for each group, yuou can add members. It is something like Trello Boards, but I think its better.
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 No calendar integration
Does not have calendar integration
Con Doesn't support multiple reminders
