I prefer digital, but everything's a mess. Within digital, compared to notes/calendars/reminders, sending emails to myself is the most effective for me since I end up cleaning my inbox quite regularly and to clean I delete useless stuff, archive dealt with stuff, and pending stuff remains in my inbox. Rent payments for example will be an alarm, calendar with reminder, and email to all my accounts and my wife's. Whenever I do write, it's for a specific task and much better implemented.