I'd say asking about which airsoft manufacturer to go with is maybe a better question.
as for models...
-glocks are fairly versatile when it comes to modern loadouts. used by military, police, pmc, security etc.
-P226, as above, nicer but heavier.
-1911 is more versatile for guerilla and civilians... some yankie loadouts as well. 1911 also is very versatile for upgrades, not great for shooting thou.
-something like makarov or tokarev is also a great choice for guerilla or eastern armies.
-m9... think some yankie outfits? also a fairly generic gun in general..
also think if you want a rail. great for a torch, but makes your gun look more modern/western