I've been experimenting with Taskpaper for lists over the last couple of weeks, and really like the flexibility. All of my lists are stored as text files in Dropbox, which makes it easy to use/update lists from anything or anywhere. On my iPhone I use Drafts to quickly add to the task lists and Editorial to work with the tasks.
On the desktop and laptop, I've settled upon using vim. Davidoc/taskpaper.vim gives me all sorts of neat ways of dealing with .taskpaper files, and has been working pretty well so far.