Both are really useful. The marking gauge you linked allows for left and right marks which covers it all.
They are indispensable for me when marking lengths for fitting mitered trim around boxes, The flat side allows the mark to be exactly in-line with the surface measured against. Tablesaw cut is then set to just remove the line.
Marking gauges are useful for layout, but choice of a wheel/blade/pin are kind of personal. Wheels can wobble, pins and blades can follow the grain when marking a board edge. Adjustment can also be finicky on some models.