Switching Watch faces based on the complications I want at the moment is the number one feature I need.
Apple removed this ability in the latest update. You have to long press and go into edit mode to swipe over to a new watch face.
I just to let Apple know that this change makes the Apple Watch a pointless device for me. I will stop wearing my Watch (and buying new versions) if this feature is not restored in a future update.
The point of Watch faces is that you can set them up for different contexts (Work, Workout, Communicaiton, Weather, Travel, Fancy Event, Casual Event, etc.). The inability to breezily switch between them destroys the usuability of having multiple faces set up in the first place. I hope they fix this right away.