I've been using TickTick pretty heavily since 2016, completing ~1400 tasks over this time (according to my profile page). I really like it and would reocmmend it. I use it for things that are somewhere between daily chores and big projects. My wife and I have a shared list where we track things we need to do around the house, things we need to buy, etc. I don't pay for the premium version, but here are some features that, if they were possible to pay for, I would.

My tasks for today

There's a Today view and "Assigned to Me" view. The problem with both is how they interact with shared lists. The Today view includes all tasks for today, even if they aren't assigned to me. The Assigned to Me view only shows tasks that are assigned to me, but assignment is only possible in shared lists, so my personal list tasks are not included. This means that if I'm using a shared list, I have no single view of things that I actually need to do today. I currently just use the Today view and ignore part of it.

Deadlines

All tasks can be assigned a due date, but they're dates on which you're expected to do the task. I want to express that a task needs to be done by a certain date. One way to use this information would be to inject it into the Today view as that deadline approaches.

List templates

I only have one use case for this: packing for trips. I am really bad at packing and usually start late, so I like having a starting checklist. In reality, every trip needs slightly different things, but deviating from a standard is easier than starting from scratch. I use the Apple Reminders app for this and it works really well, but of course means that before a trip, I have to use two apps if I want to remember to take out the trash, etc.

Archiving lists

On busy days (or weekends), I often like to start planning from a clean slate and list out what I need to do. It helps not to clutter this with the entire list of tasks. But once the list is done, deleting it doesn't feel right because it deletes the tasks also. I would like to be able to archive instead.

I could use tags or clear my Today view before I do this, but a new list usually feels better. I would use this for packing, grocery stores, busy weekends, etc. Currently I switch over to use Apple Motes for this with a checklist.

Shared groups of lists (folders)

You can share multiple list with others, but only one at a time. Especialy for sharing with my wife, sometimes one list just isn't enough, even with the organizational capabilities of tags and sections. We already have a shared folder in Apple Notes and Google Drive where we can arbitrarily create nested items, so it's a familiar pattern to add to our shared task list.

Family premium account

For all the features, I would like to be able to pay once for both my wife and I. Currently, shared lists fall into a weird place if one of us has a premium account. Some features essentially become read only, and can make for a weird experience.

Advanced Smart Views

This is nice to have, but in one of the iterations of trying to organize our tasks, we were using the same tag across lists. The tag view then shows all those tasks (as it should), but I wanted to sometimes see tasks with a tag from only one list. A generically advanced way to mix and match lists and tags would probably have worked, although I don't think I'm using the app this way any more.

Repeating tasks that don’t pile up

It's possible to make tasks repeat, but last time I checked, repeating tasks pile up if you don't do them. I would generally use this for things like "make lunch" or "floss", for daily tasks, so once the day is over, I don't need to know that I missed it yesterday. Chances are I didn't miss the task, I just didn't mark it down. To be fair, there is a Habit tracker feature that probably works this way, but I'd rather have the tracking of the habit be an stats embellishment / gamification addon to a repeating task, rather than a separate feature.