Left: Next! - Right: Task ThisiOS: Task This: Free Task This goes above and beyond the call of task master. It fully integrates with your address book to attribute people and events to your tasks such as reminders for phone calls, meetings or even when an upcoming Birthday sneaks up on you. Additional features includes confidentiality configurations, shopping lists and synchronization with their web app on top of the easy to get into task lists. It's helpful, beautiful and overall satisfying for iPhone/iPod Touch users. iPad: Next!: $10 Next! has a little bit more of a learning curve but is an integral part of the iPads app arsenal when given the chance. It doesn't flood the screen with unnecessary buttons and prompts but rather makes smart use of gestures to bring everything within reach. The best thing about this app is how it feels like there's a birds-eye view over all projects. There's also the option to store reference material so information is never too far from reach.
Left: Taskos To Do List - Right: Task List - ToDo ListAndroid: Taskos To Do List: Free Lay it all out for this app and it'll bring peace to chaos. This app looks gorgeous while displaying several types of tasks organized under personally applied tags and folders. Lists can be categorized, given alerts, attach notes for additional detail and even integrated with Facebook friends, Twitter followers, WhatsApp and gmail contacts. There's also syncing options with Dropbox and Google tasks. Task List - ToDo List: $2 For those who need a more personal environment there's Task List. Tasks are organized into different classifications and the main page displays impending tasks based on importance. Each task can be assigned an icon, priority setting and can be sorted as such for quick and easy access. Overall more eye pleasing and provides more bang for your buck.
WP7: Tasks: Free Add a little color to your life with Tasks, the charming little number that borrows WP7 tile look to amazing effect. It has all the bells and whistles. Alerts, sorting, categories, priorities, deadlines and themes all help this app to be the best in the Windows Phone Marketplace. Tasks is easy to get into with great attention to detail all while staying true to the Windows Phone theme.
Cross Platform: Wunderlist: Free If you have access to the web or require tasks to follow you, then look no more then Wunderlist. Apps are available for Android, iOS, OS X, Windows and Linux. In the event that any of the above aren't viable options then Wunderlist can still be accessed through the web. What makes Wunderlist worth mentioning is its cloud based syncing. If a task is checked off of one, then it checks off on all. It's not the most advanced by far compared to any of the others but what makes it worth mentioning is how well it works. It's simple, free and available by any means necessary.