iOS: There are many options when it comes to managing to-do lists on iOS. If you're looking for something along the lines of the incredibly popular Clear app, but with more features, One List is worth a look.
One List takes the simple, coloured block idea from Clear, but it adds some features. You can organise your to-dos by colour-code priority blocks, build daily reminders, add tasks to the Notification Center, and customise the colours with various themes. If Clear is a little too simple for you, and Any.Do isn't quite meeting your needs, One List might hit the sweet spot you're looking for.
One List (free) [iTunes App Store]