My answer was serious. I've tried computer "to do lists" many times. None are as fast, convenient, accessible, or inexpensive as a simple notebook and a pen. Sometimes the best solution does not involve a computer.

I rewrite my tasks each day. This tends to have the side effect of making me complete those nagging little ones that sometimes seem stay forever.

To prioritize, I just put a little star next to the important tasks. I tried using different color inks and annotating with categories in the past but found this to be a waste of time.

It is a permanent record that I don't have to worry about backing up. I've got notebooks going back over 20 years now.

I guess one down side is that one cannot data mine it, I question the actual usefulness of such an activity.