Don't take this the wrong way but this question, and others like it....380 vs 9mm....45 vs .50...has been done to death, they are so last year. And every time we only learn one thing, that every one has an opinion on way or another.
The simple fact remains that on one here can answer the question, other than to say, go to your local range, try out a few guns, different styles, different calibers, and find what works for you.
Me personally, I love the stopping power of the 40 cal, but the simple fact remains that I can put more rounds on target, faster, with a 9mm. But that is me.