A few weeks back, I began to use Things 3 as my main task management app (or simply my to-do list app). Before that, I was using TickTick, which is also a great task management app!
What I like about Things 3 is its simplistic UI, accompanied with the suitable organisational features for me, and the great user experience.
First, the UI is so clean and so simple. One look at the app and you should understand.
Besides, one of the organisational feature that I love the most is having a separate deadline and a "When?" date. It allows me to plan when to complete a task without affecting its actual deadline.
Lastly, the user experience is awesome! I can just select multiple tasks and drag them to anywhere. Dragging tasks to different locations will have different effects. For example, dragging tasks into different Lists and Areas will move them there, while dragging tasks into "Today" will set a deadline of today. Such designs are ingenious!
The only thing I miss in Things 3 when compared to TickTick is the lack of Markdown and attachment support. The lack of Markdown support is a big one for me cause I use it a lot. I would be really glad if such features comes in the future, but I am alright if they do not, since it is the lack of all these features that makes Things 3 unique - clean, simple, fast.