Depends on how long you stop for. The DSA (who run the Driving Test) recommend that in an auto you apply the h/b when you stop. In real life, if you have a "temporary" stop, just up to 30 secs or so, then hold it on the f/b unless on an exceptionally steep incline. For "extended" stops, say lights with a regular time pattern or pedestrian phases, then use h/b (if needed) & "N" to save heating up the torque converter neeedlessly & saving a small amount of fuel.