I don't show the fitness rings on the watch face as a complication, but I do have it turned on because I like the stand reminders. Everything else is off, though (the activity updates, achievements, etc).
I do have the HR sensor active as I like to look at the history. I take a beta blocker for blood pressure and one of its effects is to lower heart rate, so being able to see if it's going too low or too high is helpful. I can look back over several days and see if there's any trend.