Best handgun for combat use and protection purposes?

As i have asked above, i am looking into getting a good handgun for self defense and if necessary, combat use, i want a good handgun with a lot of stopping power, i have heard that .45 ACP is one of the best for stopping power and was wandering if this be the case which handgun is best for firing this round, i appreciate any answer someone may have, p.s. i appreciate it if no one does the whole "if you don't know you don't need it answers, those bug me, anything that is actually trying to help me out i appreciate it^^