Ask HN: what do you think is the best UI for setting up recurrence?

Recurring tasks, reminders, emails or deliveries. Anything where you have something that should re-occur on some schedule.

What is the best UI that you've seen for configuring this?

- Free form text field, i.e. typing "every 24 hours"

- Classic form, dropdowns and radio buttons (examples would be appreciated)

- Crontab...

- Something else entirely