I'll recommend any 9mm you can hit the target with and that has a comfortable grip and trigger for a carry. Make sure it's reliable before stuffing it in your waistband as well. If you can't make it to the range every week at least once, I recommend going for a compact rather than a subcompact and as much training as you can squeeze in.
I personally carry a Glock because it fits all of that criteria for me. My second choice would be a toss up between the M&P9 and the PPQ.
"Intelligence is nothing more than discussing things with others. Limitless wisdom comes of this." - 山本 常朝