Quire

It is super easy and doesn't have any fluff or bloat

Missing some integration capabilities (last time i checked: webhooks) and their API is not available in many automation services (yet)

Simple.

Fast.

Intuitive.

Not distracting.

Gives everything a freelancer, SMBs or corporate might need.

It's not overly complicated with unnecessary features.

Tree structure is absolutely awesome! This way you can break every project into actually manageable tasks.

Every task or subtask can have priority, start and due date, responsible person or external team and files attached.

FREE.

Minimalistic view might give an impression it's super basic and won't provide what you need [but the truth is exactly the opposite].

Some people might find lack of chat or message board a disadvantage [but for me tasks comments are enough and allow me to keep things tidy].

There is no calendar view so it can be seen as a negative by some people [but there is a timeline view which is good enough for me].

Not sure how pricing structure will look like in the future.

Simple UI
Easy inline entry of tasks and restrictions such as due date, start date, assignees, tags, files and everything else one could need to get their tasks in order and their team up to date
In line chat and descriptions let people talk about important issues
The overview and kanban board options are great for people who organize their information in different ways, and the ability to have the boards interact with one another in various ways is excellent

Very minimalistic (A positive for me, but maybe not for everyone!)
Constant improvements being rolled out (A positive for me, but not everyone wants to have to learn new features constantly)
FREE!

Everything, but i Prefer:
- Possibility to assign a single task to multiple user (and when it's get done, it goes away for everyone)
- Possibility to organize yours tasks by organization, projects and boards
- Possibility to create weekly, monthly, etc tasks
- Possibility to attach document to each task
- User friendly
- French language ! (and the translation is good!)
- The generosity and help from the customer service (as a small and poor charity organisation who rely on volunteers who work from home, we need this kind of service to complete our projects)

- maybe the fact that when you look a subtask on a board , you can't see their connection to the "complete task" and it can be somewhat confusing to differentiate between similar subtask (Actually we just have to always name the subtask with the name of the complete task, so we have a way around)