I think the most common pistols are going to be the ones that are entry level, no nonsense and easily available. Glocks, Rugers, S&W M&P's. Cz's, 1911's, Sigs 22x, Beretta's, HK USP's, Torkarev,s Norc's and the like. Almost every gun owner I know has a Glock just for the sake of having a pistol. Walther PPx's, Sterys, HK P7, Stryke ones, FNX's, desert eagles and so on are a little more "exotic" and by that I mean they are pricer than the next brand equivalent or are not as available at every LGS you walk in to. Basically ghostie nailed in.