When comparing Things 2 vs Todo.txt, 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 Things 2 is ranked 24th. 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 Cloud sync
Users need to create an account for Things Cloud (the account can be created from any device). Once signed up, cloud sync will be active, and you’ll have to login on all of your devices to complete setup. From that point on, syncing happens in the background. It is invisible and always reliable.
Pro Daily review
At the beginning of every day, a yellow box appears at the top of the Today section, displaying all tasks scheduled for this day. You can investigate them, and then decide which ones you’ll have for that day and which one you’d rather want to delay.
Pro Easy to set up and use
Things 2 works from the moment you start it up. Simply add a task and when you want it done by. You can also add notes to tasks or tag when you need them. Things allows you to quickly and easily start keeping track of your tasks.
Pro Project support
Things 2 has a projects feature that allows you to organize your tasks together. You can select a project you need to get done and Things helps you focus on each task to get it done. You can even group projects together to focus on the most important aspect of your life at the time.

Pro Great for GTD
Things is one of the best apps of doing Getting Things Done.
Pro Nested tags
It's very easy filtering tasks that belong to various areas (etc private vs work)
Pro Responsive and easy naviagation
Logical and responsive navigation and editing. Easy to operate.
Pro Customized calendar
The calendar view (when selecting a due date for a task) is a customized, scrollable version of the default iOS calendar view. This makes it look familiar, but also functional for Things 2's requirements.
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.
Cons
Con Expensive if you buy apps for Mac, iPhone and iPad (all sold separately)
As at May 2016 if buying all three apps it cost $80! That said there is no annual subscription and I've been using Things for years and have only paid once so far.
Con Poor calendar view
Could be more convenient with calendar interaction. Not an ordinary approach for visual people, if you want to see all the calendar events in the familiar format.
Con No file attachment available
Con No supported time based/location based alarms
Other apps have these abilities, and they are very useful. Especially for a $10 app, it would be great to include these premium features.
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.
