When comparing TeamWork.com vs GTDNext, the Slant community recommends GTDNext for most people. In the question“What are the best cross-platform task apps?” GTDNext is ranked 13th while TeamWork.com is ranked 50th. The most important reason people chose GTDNext is:
All the “Get Things Done” lists you would expect: next actions, someday, waiting, and scheduled.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Offers lots of granularity in task management
Tasks are grouped in task lists and can have subtasks. Each task list can be assigned to a particular set of users, aligned with a milestone and have notes. Each task in the task list can have a description, a start and a due date, attachments, priority, manually set progress, followers, dependencies, be assigned to a particular set of users and set to repeat. Each subtask has the same configurable properties except instead of the ability to assign people, subtasks can be commented on.
Pro Each project has only the required functionality
It's possible to limit projects only to the necessary features so that unnecessary functionality doesn't get in the way and clutter up the interface.
Pro Good assortment of features
Gantt charts, calendar and an easy overview of huge amount tasks.

Pro GTD style lists
All the “Get Things Done” lists you would expect: next actions, someday, waiting, and scheduled.

Pro Automatic next actions
When it comes to choosing your next action, most to-do apps suffer from the same problem: All of your actions (sometimes hundreds in total) are visible to choose from. This can overwhelm users and cause them to give up on the system. GTDNext is different. In the "Next Action" view, only the very next action is shown for each of your projects. This results in a nicely consolidated view of only the things that need your immediate attention.

Pro Unlimited levels of projects and actions
In GTDNext you can set up an unlimited number of levels for your projects and actions, allowing you to plan your project and sub-projects in as much detail as needed.

Pro Areas of Focus
GTDNext supports the “Areas of Focus” methodology from Getting Things Done. You can filter all of your tasks to just show your work tasks, side project tasks, or personal tasks. There is also a global filter, so that when you’re hard at work you can focus only on your work projects and tasks.
Pro Option to visualize all projects and tasks in a single outline view
This is really useful because it prevents you from having to navigate through each project individually.

Pro Many keyboard shortcuts available
The number of keyboard shortcuts makes it easy to log or add tasks without removing your hands from the keys.
Cons
Con Provides too much detail for small projects
Amount of granularity for tasks can be overwhelming for small projects or teams.
Con No mobile app available
Con Web only
GTDNext does not have native apps for other devices, but it does work across PC/Mac/Linux on the web client.
Con No Google Tasks integration
