For a range gun, I would go with the 9mm for the less expensive ammo.
For a target gun, I would go with the 9mm for the accurate loads and low recoil. For a self defense gun, I would go with the 9mm for the higher capacity and preformance of the best 9mm JHPs. For every every thing I can think of, the 9mm stands out as the better choice between the three caliber you asked about. 9mm is one of those rare win-win situations. It is low cost, accurate, powerful and you get more rounds in a gun chambered in 9mm than you do in .40. I have never seen anything that says in real world gunfights, the .40S&W is better than the best 9mms. It would stand to reason that the .40 would be better but it sure doesn't seem to be so much better that anyone can tell.
I love my 9mms because I can control them and shoot them as often as I like. I also love .45s because I find them very controlable as well. the .40S&W can be a nasty little round to try and control if firing rapid fire with one hand. This is my benchmark in how I can control a handgun designed for self defense. I figuire that this is the way it will most likely be shot so if I can't handle it, I don't need to own that gun. The Beretta 92fs is right at my limit of being able to control it one handed rapid fire. If it were any bigger, I think I would start to lose control. The Kahr K-9 is a fistful of gun and I feel like I would never lose control of it since it fits so wel in my mitt.
For a target gun, I would go with the 9mm for the accurate loads and low recoil. For a self defense gun, I would go with the 9mm for the higher capacity and preformance of the best 9mm JHPs. For every every thing I can think of, the 9mm stands out as the better choice between the three caliber you asked about. 9mm is one of those rare win-win situations. It is low cost, accurate, powerful and you get more rounds in a gun chambered in 9mm than you do in .40. I have never seen anything that says in real world gunfights, the .40S&W is better than the best 9mms. It would stand to reason that the .40 would be better but it sure doesn't seem to be so much better that anyone can tell.
I love my 9mms because I can control them and shoot them as often as I like. I also love .45s because I find them very controlable as well. the .40S&W can be a nasty little round to try and control if firing rapid fire with one hand. This is my benchmark in how I can control a handgun designed for self defense. I figuire that this is the way it will most likely be shot so if I can't handle it, I don't need to own that gun. The Beretta 92fs is right at my limit of being able to control it one handed rapid fire. If it were any bigger, I think I would start to lose control. The Kahr K-9 is a fistful of gun and I feel like I would never lose control of it since it fits so wel in my mitt.