Whatever you choose, make sure to practice a lot with it. It is amazing how long it can take to draw your weapon or reload, under stress. Practice makes perfect. I don't know your shooting experience, but I try to shoot 2x per week.
I don't have (or need) a CCW, but if I did, I'd go with the S&W M&P 9mm or the Springfield XD 9mm. I like both of them, but I'm a little more partial to the M&P. I just like the idea of a 9 for a concealed carry. Still strong enough to put someone down, but they're generally smaller, hold more ammo, have less kick and cheaper to shoot than a .45.
Some of the best advice right there. I tell anyone planning to purchase a firearm for home defense. You need to practice so that it becomes second nature and you can operate it efficiently when half asleep. Same goes for CCW use and stress situations.