Whatever doesn't taste burnt. Don't overthink this - its as simple as starting at low watts and clicking to the watts setting where you find the vape tastes best. There's no set answer because wick and coil performance can vary even with the same kind of toppers - there are different juices, different taste preferences. If it starts tasting too hot for you or a bit burnt you know your limit - click down to where it tastes right. Then stay at that watts setting. Your Tesla reads the resistance of your coil and sets the volts automatically for the watts - all you need to do is choose the watts setting that tastes just right.