While my personal favorite is the 40cal, at work I can only carry 9mm. For this reason I practice and train with my 9's weekly. So much so that my EDC has become 9mm.
.357's and 44's aside, the 45 is the "big dawg". That's a fact. There's no disputing it's stopping power. You just have to be certain of your shot placement, (under pressure). My point is, is the .45 the caliber that basically is what you like and tend to shoot at the range, or do you actually train with it?
Here's the thing... Pick a gun and a caliber that you're completely comfortable with. Know your firearm. LEARN TO HANDLE AND SHOOT IT WELL! Practice, practice practice. Then practice some more. Learn to shoot it well with your strong hand only. Then learn to shoot it well with your weak hand only.
Shooter's point is spot on. Pick a firearm and get good with it!