When comparing Todo.txt vs Toodledo, the Slant community recommends Todo.txt for most people. In the question“What are the best cross-platform task apps?” Todo.txt is ranked 9th while Toodledo is ranked 23rd. The most important reason people chose Todo.txt is:
Todo.txt can be edited in plain text and then displayed with neat styles.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Easily editable format
Todo.txt can be edited in plain text and then displayed with neat styles.
Pro Editable from any text editor without needing any proprietary software
Because todo.txt is just a todo standard with various compatible apps to edit it, you can update it from any device as long as it can edit text and you can access your todo.txt file
It's convenient to be able to access your todo list quickly via your programming environment so you don't have to switch contexts, and to have a separate todo.txt file per project.
Pro Works with lots of apps for every platform
Todo.txt lists can be edited in virtually every text editor ever made and accessed on devices that support Dropbox. The user community has also created a number of apps for dozens of platforms.
Pro Command line support
You can edit your lists using the command line (e.g., Terminal) via a supplied bash script.
Pro Full control over your to-dos
You have full access to the underlying programming rules, and therefore total control over your task lists.
Pro Extensible
Has been extended to include most things people want, including a multiple of interfaces and app for all platforms.
Pro Easy syncing
Todo.txt automatically and seamlessly syncs through Dropbox.
Pro Wide range of interface apps
The community has developed a wide range of apps that interface with the basic file structure. These apps vary in how much they accomplish, how much hand-holding they do, their level of glitz, etc. They range from plugins for an editing app like vim to stand-alone, platform-specific GUI's. So YMMV depending on what you use. (todopy is particularly nice, a Python program that has a "console" mode which provides a keyboard-driven GUI.)
Pro Follows the unix philosophy
Does one thing: to do lists
Pro It's free
It runs on MacOS, Android, and Python (in the Mac's Unix CLI) -- all for free.
Pro Easy to sync up between lots of devices and interfaces
At a bare minimum you just need to be able to edit text, but there are many apps and advanced interfaces you can install on many devices to supplement your to-do list editing.

Pro Can create to-do items via email
It's possible to create a to-do item by sending or forwarding an email.
Pro Decent filtering and sorting
Pro Priority organizing
Pro Great GTD implementation
The GTD principles are very perfectly supported by Toodledo.
Pro Functionality-rich
Integrated sharing, note taking, habit tracking, and outlining make this a more powerful tool than a simple list of to-dos.
Pro Upload From CSV
Quickly upload an excel (CSV) file template of tasks to a folder for complex but repeating projects.
Pro Well documented, free-to-use JSON API
If you adopt Toodledo as your productivity system, you can be confident that you can extend it to fit your needs with this programmatic access.
Pro Can tag items
Pro Space to add lengthy text
Notes area that can then be hidden.

Pro Sends a daily email reminder
Toodledo reminds you via email of the tasks on your plate for the day.
Pro Apple Watch support
Integrated support for Apple Watch lets you check on your to-dos on the run.
Cons
Con No support for reoccurring tasks
Tasks have dates corresponding to creation and completion, but there is no explicit support for due dates or for tasks that reoccur.
Con Nested tasks not supported
Many todo tasks for developers end up having sub tasks that need to be performed for a parent task to be completed, but the todo.txt format does not have any nesting.
Con Android app not updated since 2013
The app only seems to support Dropbox. It would be nice to see support for different and newer file storage services.
Con Free version limited to 20 folders
Con Android app has annoying notifications
Whenever the app fails a background sync action for any reason (server issues, lack of internet connection, etc.), a notification appears.
Con Good as a starting point
Toodledo is a good starting point, but is essentially the same as an Excel spreadsheet where you have to build your workflow via the saved searches.
