For most users, a fixed-body indicating plug gage, whether mechanical or pneumatic, is probably the easiest gage to use to get a fast, high-precision and accurate hole diameter. Simply insert the plug gage into the hole and read the deviation from the master to get the diameter.
However, the real advantage of these types of gages over an adjustable bore gage is that it is a lot easier and faster to determine hole conditions such as ovality, taper, hourglass or bell-mouth shape. All it takes is a further exploration of the bore.
