Water usage is probably my biggest. Living in a high desert, my wife and MIL see no problem with filling one side of the sink with hot soapy water to wash a few dishes because “that’s just how I’ve always done it”, to watering the grass and plants for hours. All of this makes me mental.
In pretty much the opposite direction, my hill is that “right”,“wrong”, “blameworthiness” and “praiseworthyness” are concepts that people are in general allergic to critical thought towards, and they are EXACTLY the concepts that people should be approaching in order to have a better life and to make a better world.