I prefer semiautomatic guns, but that's because I'm scrupulous about maintenance. If I wanted a gun I could take out of the drawer 6 months later with no doubt that it would fire, I'd choose a quality .357 Magnum or .38 Special revolver from Smith & Wesson or Ruger. My top choices would be the Ruger GP100 4", Smith & Wesson 686 4", Ruger SP101 3", Smith & Wesson Model 60, Ruger LCR, and Smith & Wesson 642, in descending order of size.
My grandpa's old Colt Python isn't a safe gun, we shoot it and my dad tucks it under his truck seat on long trips, and sometimes it does nightstand duty. Every time I take that gun out of its leather it so obviously is ready for action. Revolvers give you a great deal of confidence in their steadfastness.
Beretta PX4 .40 S&W - Beretta 92FS 9x19 Para - Rock Island Armory GI 1911 .45 ACP - Colt 1968 Detective Special .38 Spc. - Ruger LCP .380 ACP - Daniel Defense M4V1 Carbine 5.56x45 - Ruger 10/22 .22LR - Remington 870 Express Tactical 12GA - 1943 Izhevsk Mosin-Nagant M91/30 7.62x54R