Which ever one you are most comfortable changing. Estlcam setting I would assume would be the easier of the 2 for most people. Start with something slow like 1 mm/s and move up from there. You never said how fast you are trying to move it. I can’t give you a number because everyone’s max setting will vary depending on how easily there axis moves. Or take whatever acceleration settings you have in the firmware for the z axis and cut it in half that should help as well. Or do both for good measure. Only increase them if you are bothered with the speed at which you are moving.