Waiting patiently for Pocket Informant. I used it on windows mobile back in the day, and then on my BB, and it is almost out for android. I think their interface and featues is second to none.
Cloud List is easy to setup and use on different handhelds, has a web site where you can look at the lists. Easy to share with other people for items like to do lists, grocery lists, punch lists, etc.
I personally have been using the tasks that Google provides since it is integrated and can be accessed from the web or the phone. There are many apps that can access these.
I am a huge fan of integration like that, it just makes life easier.