I know there are a ton out there, so i was hoping someone could help me narrow down the options. iPad-specific apps would be great, but not necessary.
"Epic Win" is fabulous, with it's only downside being that it is a bit on the large side at around 50 megs.
When it comes to todo lists I prefer keeping it simple. Which is probably why I like Do It Tomorrow so much. It's pretty much a paper pad ui modeled after a moleskine notebook with a clean interface for quick info - date, current list, add/remove tasks, random coffee stain. My favorite feature is that whatever tasks you don't complete get pushed to the next day automatically, so you no longer have to micromanage a calendar. Also it is Retina grade, free, and has no ads at all. If you're looking for something a lot more intuitive than the native notepad app in iOS I would check this out. Do It Tomorrow
I've tried loads, and my favourite is 2Do by GuidedWays. It's super slick, has that Apple-like simplicity and usability, and has a desktop sync as well as over-the-air sync to MobileMe and ToodleDo. BTW, this is on my iPhone4, so I'm not sure if its iPad too.
I've been using Pocket Informant from my Palm OS and Blackberry days. Now on my iDevice, this one is a keeper and helps me run my day.