Well, I'll say a 9mm Glock, just based on personal experience, shooting a lot of rounds thru a lot of different handguns...BUT, let me throw a wild card out there...The Ruger P series 9mm auto's. Yea, inexpensive, and a little "clunky", but I spent several years training an agency who issued that weapon, and it was just as reliable as anything else, and better then most...Put some of the "elite" brands to shame. Only problem I seen with that series gun was the magazines were easily damaged when people stepped on them during reloading drills. This is based on stock of armory issued weapons, with new classes coming thru every month, and who knows how many thousands of rounds fired thru them...
Larry