I really like Taskito, and have been using it for quite a while. I think the widget looks very nice too, though I relied more on the notifications.

Recently switched to Microsoft To Do, simply because I realized it works more in the way I think. I make a plan for the day, and tick off the tasks I finish. Some tasks might not be finished (happens a bit too often, I admit), and those tasks will be suggested when I make a plan on the following day. The widget looks OK, not too exciting, but clean enough.