The Book of Five Rings tells us to have no favorite weapon but to master as many as you can.
That said all around favorite would be the 1911 series pistols in .45ACP If I ever win a big lottery I would like to go hog wild on making one an everything gun with a .22 LR conversion kit, old .38-45 set up, .38 super, 9x19 (not sure how to deal with the ejector issue) and .40 S&W set ups, as many Springfield armory SASS units in as many different calibers as possible and shell shrinkers and a carbine conversion unit. What lower case survivalist could refuse such a dream?
In a 9 silly meter CZ 75
In a largish revolver S&W 27 (.357 is enough, thank you very much)
In a service revolver 4 inch S&W Model 15 or 19
In a little defensive revolver I actually like the Charter Arms under cover with bull dog round grips better than S&Ws.
Smallish auto shrunken 1911 clones like the Colt Mustang or Star S series
Single shot Merrill or who ever was making it when last seen.
Least favorite......Type 94 Imperial Japanese Army pistol
-kBob