I'll go first.
I feel my best whenever my BS is stable (a flat line on my CGM) for an extended period of time between 110 and 150. When I'm between 90 and 110 I usually feel good too, but I sometimes get low BS symptoms.
I feel my worst whenever my BS is between 180 and 210 -- for some reason I get more pronounced high BS symptoms in this range than I do when I'm over 210, I'm not really sure why. I also feel my worst when I'm below 70, and when I'm on a very sharp downward trend.