When comparing Things 2 vs Checkvist, the Slant community recommends Checkvist for most people. In the question“What are the best cross-platform task apps?” Checkvist is ranked 20th while Things 2 is ranked 24th. The most important reason people chose Checkvist is:
Checkvist hits a sweet spot between minimal and complexity. It gives you a host of options and extras to use on your lists, but you can completely ignore them if you don't need them and keep it very simple. This makes Checkvist a one-stop shop, regardless of what type of 'list' you need.
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 As simple or as complex as you need
Checkvist hits a sweet spot between minimal and complexity. It gives you a host of options and extras to use on your lists, but you can completely ignore them if you don't need them and keep it very simple. This makes Checkvist a one-stop shop, regardless of what type of 'list' you need.
Pro Tasks can be managed with custom tags
Pro vim-like commands
Pro Convenient search by text or tag filtering
Pro Converts incoming emails to todos - this is a way to enter tasks from anywhere.
Pro Great search
Search filters help you search for tasks by tag, due date, assignee, etc.
Pro Very flexible
To-do lists often need to be grouped and regrouped for clarity. The outline-based nature of Checkvist makes it easy to move things across categories, to increase and decrease priority, etc.
Pro Smart parsing of items
Parses markdown, html links, hashtags to become formatted text, clickable links, and tags, respectively.
Pro Generous set of free features
Checkvist offers many free features if you are using this individually.
Pro Supports comments on tasks
Any item can have a free-text comment, which can be shown or hidden as desired.
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 Limited capability in the android app
Checkvist is primarily a web interface.
