There are already many sorting options for lists, but I'd still like to see another one, if I didn't miss anything:
Like creation date and due date, I would like to sort by completion date (forwards & backwards). You know, due is the theory and completion is the reality... 
Maybe in a future update.
Hi @thx, thanks for the feedback.
Current 'Due Date' sort option is basically same with completion date. When a task gets completed, it's sorted by completion date.
So if you make a smart list with its own sort option of 'Due date' or 'Due date (reversed)', you'll get completed tasks sorted as you want.
Thanks!
All right, that makes sense.