Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Habitica - Habitica is a free habit building and productivity application.
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.
Strides - Track all your goals & habits in one place, with flexible reminders to hold yourself...
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Streaks - The to-do list that helps you form good habits.