I like shooting .45, but I like buying 9mm a LOT more 

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Depends on the application. Inexpensive target practicing.....9mm. A round I can count on to totally "F" someone up.........45acp. As far as capacity is concerned. Yes, more is better, I will not argue that. How could you? BUT, if you are TRAINING often like you should, then you WILL NOT need a but load of rounds. I train on a weekly basis with ALL of my pistols........yes, even mah 9's, but when it comes to my primary carry weapon it's almost always going to be a .45acp.
The key is TRAINING.....not target practice! Real, under stress, realistic action shooting. If you are fortunate enough to own rural land I suggest you set up a small training course and run some action drills. At my house I have built a small course consisting of various walls, targets and obstacles which recreate some of the possible scenarios I could face in a day to day setting. We often switch up the drills to keep it fresh. We almost always use a stopwatch just to add that factor of pressure and competitive drive. Each wall or obstacle is a different checkpoint from which we move to and fro in various order. We have numerous targets in different positions that we shoot at from the various checkpoints. In this course we will shoot at 10" - 6" metal plates from 25yrds - less than 5yrds. During these scenarios we incorporate mag changes and deliberate jams. We also run the course with our carbines. You wouldn't believe how much better of a shot I've become under these conditions.
Uh.....back on target here. The .45acp is the clear winner for me.........but it dont make a difference what you carry if you ain't prepared to effectively use the dang thing.
Chuck Norris shoots a .45acp...............therefore I shoot a .45acp.