Hi-Capa 5.1 - A double stack, ambidextrous and highly customizable competition 1911. Hi-Capa is used for airsoft versions of it though, so call it what you will. These should be rare, expensive and top tier pistols.
The weapons should be highly customizable, ranging from various pistol grips to rail systems, vertical foregrips, color options, furniture options, sight options, railed frames and threaded barrels for pistols and much more. As for add-ons, I'd like to see the following (excluding gun-specific add-ons, such as pistol railed frames or R.I.S. systems - those should be upgrades).
Silencer - Universal silencer with adapters like in the current games
Reflex Sight - 1.5x Reflex sight with red/green reticle illumination, perhaps multiple reticle options. I like the look of Trijicon's.
Pistol LAM Unit - Combination of a powerful Xenon flashlight, a red laser sight and a green laser sight
LAM Unit - Full size LAM unit, same as above but bigger and brighter flashlight