I have argued and will continue to argue that with modern firearms, it may be true that one gun is superior to another in various aspects (reliability, accuracy, stopping power, etc), but only marginally so. With few exceptions, any modern firearm and cartridge built for defensive purposes will be effective - the only variable is the user.
For myself, the 1911 is the most natural feeling firearm in my hand (my XD has become a close 2nd). I like the trigger, I like the way the gun feels when it fires, I'm comfortable with the features. I like the way a .45ACP cartridge feels when it discharges. Therefore, the 1911 is the best choice for me.
My girlfriend prefers the Beretta 92FS. She feels the same way about the Beretta and the 9mm cartridge as I feel about the 1911 and the .45ACP. This motivates her to shoot more often, she becomes more skilled with the gun, and therefore becomes more effective with the gun.
I know some people will argue this point, but if fired accurately, a quality 9mm JHP round is just as effective as a similar .45ACP round. The question is, can you fire both with equal accuracy. Personally, I hate shooting 9mm (I make an exception for full auto, of course). I don't like the way it feels coming out of the barrel, I don't like the way it sounds, I don't even like the way it SMELLS. For me, firing a .45ACP round is like [insert simile of pleasurable male biological activity].
So point being, pick a gun and fire about 500 rounds. Pick another and fire another 500 rounds. Guns retain their resale value fairly well. Repeat as necessary, until you have a gun that you dream about shooting. That's is the most best gun for you.
But unless it's a Colt 1911A1, it's not THE best gun.