TickTick

I've tried tons of different todo list apps. Todoist, Microsoft To-Do, Google Tasks, Any.do, etc.

This is the only one that's stuck. A large part of it is I use many different devices and TickTick works great on all of them. Others, like Things, is Apple-only. I use an Android phone, Mac for work, Windows for gaming, iPad for other things. TickTick has a great set of features that works great across all of them.

My favorite feature is it's really great natural language processing. I can type "Call John tomorrow at 3pm" and it'll automatically set a reminder for me to call John at 3pm tomorrow. It also integrates with Google Calendar, which is a must-have for me. I just wish it let me add events to the calendar directly from TickTick, but it at least brings in events from Google Calendar.