Microsoft To Do – was Wunderlist.
TickTick.com – Todo list, checklist and task manager app for Android, iPhone and Web. Join millions of people to capture ideas, organize to-dos, and make the most of your life with TickTick. Available for free, syncs across iOS, Android, Mac, Windows, Web and more.
Todoist.com – The to do list to organize work & life. Join 20 million people and teams that organize, plan, and collaborate on tasks and projects with Todoist. “The best to-do list” by The Verge.
Any.do – To do list app with Calendar, Planner & Reminders | Any.do 20+ Million rely on Any.do to Stay Organized. It’s the world’s best to do list app with Calendar & Planner. Free on iOS, Android, Windows, Mac, Online & more.
Nozbe.com — to-do, task, project and time management application. Busy people and effective teams get tasks and projects done thanks to Nozbe system and apps for the Mac, Windows, Linux, Android, iPad and iPhone.
Toodledo.com | Online To Do Lists, Task Manager, Note Taking & More. Toodledo is a popular and powerful online productivity tool. Manage your to-do list, take notes, track habits, and organize ideas into outlines and lists.
Habitica.com – Gamify Your Life. Habitica is a free habit and productivity app that treats your real life like a game. Habitica can help you achieve your goals to become healthy and happy.
TeuxDeux.com – What deux yeux have teux deux teuxday? If you like making to-do lists, you will love TeuxDeux. The idea was to build a bare-bones, but visually compelling and highly usable to-do app.
OmniFocus for Mac is a great app for task management.
Things – Your to-do list for Mac & iOS.