Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Gone - An ephemeral to-do list
Vantage by 44 - Who says calendars can’t be fun?
Streaks - The to-do list that helps you form good habits.
Weekrise - A weekly task planner and to-do list.
GoodTask - Task manager based on iOS reminders and calendars