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 Python 4" .357 Magnum | Colt 1968 Det. Spec. .38 Spc. | Ruger LCP .380 ACP | Daniel Defense M4V1 5.56x45 | Alpine M1 Carbine .30 | Steyr M1895 8x56 | Ruger 10/22 .22LR |1943 Izhevsk Mosin-Nagant M91/30 7.62x54R | Remington 870 12GA