My favorite pistol would be the Colt 1911 .45 Auto.
The reasons are numerous, the history and heritage alone are considerable.
The fact that it is still one of the most accurate and reliable platforms available.
Another reason is the amount of customization is endless, at least for a gunsmith.
It is hard to beat the power and functionality.
Also the fact that most modern handguns are actually made to replace it even after 100+ years nothing truly has.
The most interesting reason is that most modern handguns also share either the design or a modification or continuance of it.
The 1911 family of pistols is my favorite.
Josh J Alaska