Grumbles' cheat sheet is incredibly useful! It is also wrong in one way that I noticed: it is not the case that Apple Watch charges equally fast with any charger.

https://support.apple.com/en-us/102454

"Fast charging requires an Apple USB-C Magnetic Fast Charging Cable."

You also need one of these power adapters:
* Apple 18W, 20W, 29W, 30W, 35W, 61W, 87W, 96W, or 140W USB-C Power Adapter
* A comparable third-party USB-C power adapter that supports USB Power Delivery (USB-PD) of 5W or greater