If the S&W fits your hand 3rd gen Smiths are boringly reliable in my opinion. I have a unfired (at least when I got it) LNIB 1989 5906 my wife gave me for Christmas. Its a great shooter. I liked it so much I put it back in the safe an bought a 3913 for a carry piece. I love the 3913. The ergos of the P9s grip are probably better than the 5906 though. Personally I'm smitten with the 3rd Gen Smiths so I would be biased towards the Smith.
Why has INTEGRITY become such a rare commodity?