There are a lot of good 9mms out there -- a whole lot. I've shot many 9mms that I would be happy with, but you asked about the BEST one.
To tell you the truth, the best gun for you is probably going to be different than the best gun for the rest of us. Only you can decide which gun is best for you and your purpose.
I guess this is a good time to tell you my "story." When I was 17, I decided that I couldn't stand it anymore -- I wanted a pistol. My Dad had a Taurus PT92 (Beretta 92FS clone), and I loved it. I decided that I wanted a Beretta .40, and my Dad said that if I saved the money, he'd buy it, and when I was old enough, it would be mine.
I saved for a long, long, LONG time -- during which, I took every chance I could get to handle lots and lots of pistols. I was in a gun shop/pawn, when I was fondling Beretta and Taurus 92s. On the bottom shelf, I happened to spy a Browning Hi Power in 9mm. This was the first time that I'd ever seen one in person, and I was surprised to see how small it was; I had always imagined that it would be the size of a 1911 Gov't Model.
The guy at the counter pulled it out for me, and when my hand and the gun met, it was a near-religious experience. Picture it something like this, except it was a gun, and I looked older:
I had totally forgotten about the Beretta that I wanted. I had to have a BHP. I finally got enough money when I was 19, and I must have bought one that was pregnant, because more have followed. I have a feeling that the litter isn't yet done being born, either.
All I can do, beyond urging you to try the same selection process, is tell you of my experiences.
I am head-over-heels for the Browning HP. I currently have 3 of them, and want more.
I have also shot several CZs, and they are excellent. I want Sigs, Springfield XDs, Kahrs, etc... but I'm just too hooked to think of anything else right now.
Only you can choose.
Wes