Honestly, the most powerful GTD software I've found is Trello, oddly enough. It's so flexible there are a myriad of ways you can use it for GTD, project management - even tracking reading lists and holiday shopping. The entire app is navigable by keyboard, and because it's not a dedicated GTD app, you can make the GTD workflow you want instead of having one forced on you. Add in the ButlerBot plugin and it's insanely powerful.
Depending on a good workflow setup, Trello can do all that's checkmarked below:
A) MUST HAVES:
✔ Tech: Must work on web (or Windows10) - No, I do not have Apple!
Architecture:
✔ 1. Area of Life (==> ability to filter everything else by Area of life. Then new stuff is automatically added into that Area.)
✔ 2. Goals (that can be assigned to Projects)
✔ 3. Context-tags (must have MORE THAN ONE Context per Action [EDIT: OR have multiple Tags possible per Action]. )
✔ 4. List field (needs a dedicated database field. GTD-friendly list names: Inbox, Next(Do ASAP), Scheduled, Someday, Waiting... or similar).
✔ 5. Today Focus / stars (easy way to select what to do today, and this list MUST be manually sort-able)
Views:
✔ 6. Easy conversion between a Project and a standalone Task... and back.
✔ 7. a Next Action per project view (i.e. a view somewhere showing just 1 [2 or 3] actions per project)
Functionality:
✔ 8. VERY easy addition of Contexts/tags to stuff (e.gl parsing of task titles and/or using either hotkeys[??] to add Context-tags)
✔ (Trello was BORN FOR THIS) 9. VERY easy moving either a task (or an entire project) between GTD Lists.
✔ 10. Ability to "bang tasks in" fast using just my keyboard.
✔ 11. Sophisticated use of colour (e.g. allocate a different colour to different Contexts-tags)
✔ 12. Lots of hotkeys
B) NICE TO HAVES:
Architecture:
✔ mostly 13. Sub-projects (projects within projects, and sub-sub-projects ==> ideally have unlimited/nested layers of hierarchy)
✔ sub tasks, not really further 14. Sub-tasks (tasks within tasks, and sub-sub-task ==> ideally have unlimited/nested layers of hierarchy)
✔ 15. Additional List(s) possible (e.g. add a "Soon" or "Later" list - not true GTD but v useful!)
✔ currently not searchable, however it will most likely come in a future update 16. a Start Date as well as actual Due Date (==> easy way of Scheduling thing for future)
✔ 16b. Ability for one Project to count towards more than one Goal
Views:
✔ requires manually labeling 17. More than one Next Action per project is possible (e.g. using "Forced Next" or a view that shows 2 or 3 Next Actions)
✔ 18. "In-line editing" (==> very easy/ very fast editing of task/project titles themselves)
19. Ability to define all own colours v precisely, rather than being forced to use basic colour palette.
Functionality:
20. Multi-line selections (e.g. move 3 tasks at once into a project - VERY important - nearly a must have!)
has hotkeys, not user definable 21. User-defined hotkeys (e.g. for adding contexts)
22. When adding tasks, they inherit a) the current Area of Life b) any current Context/Tag selected
✔ 23. Recurring tasks (ability to make routine tasks reappear at specified intervals)
C) MINOR BONUSES:
✔ Tech: Not critical but it would be nice to have an Android app. (And ability to work off-line.)
Also:
✔ 24. Estimated Time required field (==> useful for extracting tiddlers)
✔ 25. Estimated Energy required (==> useful when energy is low)
26. Serial or Parallel projects (this affects how tasks appear on Next Actions view)
✔ cards can have images, stickers, etc. 27. Manual markup of title (Bold, highlight with background colour - useful to flag critical stuff which you dont want to start just yet)
28. Advanced reporting that I can customise with my own exact logic / complex filters
✔ using ButlerBot 29. Advanced automatic formatting (e.g. certain type of content get marked up with different colours automatically)
✔ 30. Context tags to filter by always stay visible on the 'dashboard' (e.g. along top of screen?)
✔ mostly 31. Keyboard shortcuts work from anywhere (i.e. they involve modifier keys like shift/control/alt. ==> will work even text entry mode)
32. Keyboard shortcuts can be created & changed by the user
Trello won't do a lot of the work for you, however. I'm firmly of the camp that whatever app we use SHOULDN'T do all of the work for us, anyway. We need to engage and put our paws on our tasks on a regular basis. The only, and I mean ONLY, times I've felt overwhelmed or out of control were when I wasn't actually engaging with my lists regularly, but rather were dependent on software to do the work for me. But Trello can do darn near everything on your list, depending on the workflow you set up. I'm happy to chat more about how I use Trello for GTD. Bonus! It's free. So you can give it a whirl with no financial downside.
I've tried every app under the sun and Trello just really hits it out of the park for me.
