Forget Glocks. Too bulky. For my money, I like the Smith 3913. Slim, totally reliable and accurate. Many knowledgeable people call it the best pistol S&W has ever made.
Here's mine, a 3913NL with tritium sights. I can even wear it using a "Thunderwear" holster with dress slacks, and it doesn't print.
What's your choice, if limited to a 9mm?