FWIW:
Well, guess if this question had been asked a while back I'd have given a different opinion, but lately I've come to the conclusion that for an old fart like me I'd probably chose my 3rd generation S&W 6906.
I bought a new 3913 in 1995 and it has always been 100% reliable (my #1 requirement in a self defense firearm), and more than accurate enough for self defense. Recently I bought a NIB (CDNN) 6906 with a lifetime warranty for $399.99 because I found out it's the same pistol as my 3913 but in double stack. In the 3913 I was limited to 8+1, whereas in the 6906 I can use the standard 12 rd. magazine, or better yet I can use the larger capacity magazine of the 5906 (w/SW Grip+2 adapter) which is 15 rounds.
I have a Walther PPS, P99/AS, HK P7, had a Walther P99c/AS, P1, P5, Sig P239, Glock26, Browning HP, Bersa Thunder 9/UC, Taurus PT92, Star BM, KelTec P11 and probably some I have forgotten, but OVERALL I think for practical use IF I could only have one 9mm pistol I honestly believe the SW6906 would be the best choice.
For me the 6906 fits my smallish paws just right. It's built like a tank, (has a lifetime warranty to boot), I'm a lefty, so like the ambi-features, and it has a good compromise as to weight and capacity for cc. The 6906 is very easy to clean, I have absolute confidence in it's reliability, and it's certainly capable of greater accuracy than my old eyes are capable of taking advantage of.
I realize the 3rd generation S&W's aren't "cool", or whatever the term might be now, but from all I've read and personal experience they are fine firearms that are underrated, and under appreciated by almost everyone EXCEPT those folks who own them..
Just personal opinion, no offense to folks with contrary opinions.
Best Wishes,
Jesse