Round for the application
I once witnessed a gentleman at the ammunition counter of a local sporting goods store ask for a .45 auto round to use in his sidearm while hunting Brown Bear in Alaska. The young man behind the counter gave him an excellent 230 grain hollowpoint round for home defense. I couldn't not attempt to explain to this person that he was hopelessly undergunned. As we both turned to leave the ammunition counter I made this statement to him, and I quote. "The only way you're going to get any relief using that round if a Grizzly attacks is to put the .45 in your mouth and pull the trigger." He stopped in his tracks and was still standing in the aisle when I left the building. Hopefully he thought about what he was doing and did enough research to make an intelligent decision about what he needed to accomplish the task. There are many of us, me included, that will tell you what works for us. Problem is a lot of that may not work for you and you really don't want to find out that's the case after the fact (if you're still standing). There is no substitute for practice and no price you can put on your life and the lives of those you love. I love the 10MM and the .45. They both have their applications. Look at where and how you're going to be most likely to use a handgun and begin to research what has been most effective in that or those situations. You might want to search "Terminal Ballistics as Viewed in a Morgue" on this site.