I like the 9mm! I have 2 currently (CZ75B and a S&W M39) and had a Walther P-38. Practice ammo is cheap and readily available (even though I prefer to reload my own), and there is a plethora of good, reliable defensive ammo available nowadays. The M39 is currently my main CCW gun, and I have it loaded with Speer GDHPs.
I think that a lot of the 'bad press' that the 9mm has gotten over the years is no longer viable......back in the 70's and 80's, HPs that expanded reliably needed to have large amounts of exposed lead in order to do so, and feeding problems resulted...with todays newer HPs, this isn't the problem that it once was.....
I've often heard it said that "a .45 makes a bigger hole"; makes sense theoretically, but that isn't what I necessarily see in practice. RN bullets don't make 'holes' in flesh and organs...the make 'tears', and if the edges are not torn cleanly, the clotting mechanism shuts down the bleeding....even in big 'holes'. This is one reason I prefer SWC lead bullets in my .38; it acts like a 'punch press' and leaves hole that is more difficult to plug. Seen too many people shot with all manner of handguns in the past few years.....my general summation is 'anyone shot with anything .38 cal or bigger usually doesn't do well; anything smaller and they usually live to tell about it".
Just MHO, FWIW.
