RE: 9mm or 45acp???
Right now, Springfield has the best of both worlds. The XD.45 Their COMPACT model will hold 14 rounds total. 13 in the mag and 1 in the pipe.
One of the biggest reasons that people say to buy a 9mm is the ammo capacity. Now, you can carry a .45 with only 1 less round than most standard High Cap magazines in 9mm. If you didn't get the job done with the first 14 rounds, rou aren't going to get it done with that last one round either
The springfield is a great gun. I have the XD tactical in .40 and I love it. I've had several die hard gun owners of other brands shoot it and say that they just might have to buy one.
Good luck to you