Worst - Music - absolute shame that Apple didn’t create any real functionality out of the box for this widget; at the bare minimum there should have been play/pause, next/previous functionality. That third party apps (Soor, Marvis) had to come up with clever tricks to provide this is more pie in the face for Apple
Best - Siri App Suggestions (medium sized widget) - my homescreen has two small widgets up top, a medium widget in the middle and the Siri App Suggestions widget down below. Give this widget a week or so on your homescreen and it will learn what apps you use throughout the day and surface said apps at the appropriate time. This is the sleeper widget that nobody knows about. I have no actual apps on my homescreen (except for the Dock) thanks to this widget. It truly knows what I want when I want it