International Reference Ionosphere (IRI) is the international standard ionospheric climatic model. Since the original formation of the international task force in 1970s, the IRI model has been continuously improved by ingesting developments in research in ionosphere. The most current version, namely, IRI-2016, is offered with International Radio Consultative Committee (CCIR) and International Union of Radio Science (URSI) model choices with "STORM" option for the F2 layer critical plasma frequency (foF2) and BSE-1979, AMTB-2013, and SHU-2015 options for maximum ionization height, hmF2. Since these two parameters are the determining values for the other model outputs, the evaluation of the options offered by IRI-2016 is critical for various applications. In this study, all foF2 and hmF2 model options offered online at are computed for winter and summer solstice and equinox seasons of 2011 and 2015 at the locations of all available ionosondes and for all measurement intervals. The ionosondes are grouped into northern and southern midlatitude, northern and southern high-latitude and equatorial regions. Individual, regional and global model output foF2 and hmF2 values are compared with those of ionosondes in both root-mean-square (RMS) and normalized RMS (NRMS) senses. For foF2, "STORM ON" can be used any time and in any region. Equatorial and high-latitude regions have larger RMS values due to the sparse ionosondes. In northern midlatitude and high-latitude regions URSI, in all other regions CCIR is the better option. For hmF2, SHU-2015 and BSE-1979 options provide a better fit for all regions, seasons, and years.