I love me some to-do apps. I spend more time tending to my to-do items than I do actually completing the items. Hey. It's important to know and embrace your limitations. Priorities is a nice little app (US$2.99) that's already been well reviewed here and elsewhere. Most reviews leave out or report as cons the features I like most, so I'm guessing they were recently added. These include repeating task support and calendar sync. I use Google Calendar which syncs through Exchange to my iPhone, on which I now use the built-in calendar since I'm running iOS 5 and it's actually usable. On both the phone and the Web interface, tasks with a due date appear with a check mark in front of them. Very handy.
Priorities can sync with its servers or not, and it does NOT sync with Toodledo or anything else.
Behold the things that make this app useful to me: due dates, or none. Alarms, or none. Collapsable lists in which the items can individually have due dates and alarms or repeat. (There is a super option that makes the app auto-star items due that day, and starred items have a user-nameable starred-items page.)
Next is my "Inbox" page with Repeating tasks collapsed---because I really don't need to see that stuff until it's relevant, usually. Here I take a detour to say you can make multiple pages, which work like categories. I have one for errands, one for work, and so on. Anyway, here's the collapsed version:
Anything that is starred, either manually because it needs to be on my radar or because it's due that day and has been auto-starred, appears on my user-renamed "My Priorities" page:
The upshot of this system is that I have a totally maintenance-free page that tells me what to focus on that day. I don't have to specify 89 criteria for a hotlist or a focus list. I've used Google Tasks and some other super-simple apps, but I really needed repeating-tasks ability. This app is STILL super simple, but it adds a Goldilocks amount of just-right complexity for me to manage my stuff.
Disappointingly. Because there isn't much left for me to mess with.