Most modern service pistols when well made, fed halfway decent ammo, and using good magazines will be very, very reliable. That said, my choices would be, in no particular order:
* M-1911, if made as JMB intended. E.g., no MIM parts, spring steel extractor, and a 7 round mag with the dimple on the follower.
* FN/Browning High Power. My BHP Practical would be my first choice in a service auto, anywhere in the world. Energizer Bunny reliability with the best ergonomics on the planet.
* Glock 17. The best and most reliable of all the Glocks. I don't particularly like them, but I respect them.
* Ruger P-xx. I think of these as the Kalashnikov of autopistols. Strong like bull. The P-90s in .45 ACP are also soft-shooting and extremely accurate.
* Makarov. My PM has actually been my the most reliable autoloader I've ever shot. The only malf was a single failure of the slide to lock back when empty, but otherwise no failures to feed, fire, or eject.
* Tokarev TT-33. Feels like you're holding a carpenter's square but they just work.
* Beretta M92/M9, as much as I dislike the design, they are reliable when not worn out or using lowest-bidder GI mags.
* SIG M11. If I was in the service and issued a handgun, this would be the one I'd want.