Gases with smaller molecules should behave more ideally than those with larger molecules under the same conditions. For molecules of similar size, gas molecules with weaker intermolecular forces (such as dispersion forces) should behave more ideally than those with stronger forces (such as hydrogen bonding) under the same conditions.

There is a way to determine the "real" volume for a gas under different conditions of pressure and temperature. It is a more complicated relationship than the Ideal Gas Law and involves the use of experimentally determined constants for the given gas. One constant accounts for molecular volume and the other accounts for intermolecular forces. For most purposes, however, such accuracy is not needed and we will not worry about deviations from ideal behavior in ordinary stoichiometric calculations. But you should still be aware that the Ideal Gas Law is only a very good approximation and will give poor results near phase change conditions and critical points as well as at very high pressures and very low temperatures.