I would assume the clear winner if put to a vote would be a 442 closely followed by the 642.
However, my vote would go to neither of those.
The best S&W Airweight for me would be the 432PD for the following reasons.
1) Recoil of a .38 Special (forget +P) is too much for me in an Airweight J frame.
2) Recoil of the .32 H&R Magnum in an Airweight J frame is perfect for me.
3) J frame airweights in .38 and .357 get 5 rounds of ammunition. I get 6 rounds in my .32.
4) .32 H&R Magnum is no slouch what so ever. I'm fully confident carrying it for self defense. I have 85 grain Federal PD in mine at 1100fps/228ft.lbs. (compared to .38 Spec. +P 129 grain Federal HS at 950fps/258ft.lbs.)
5) It weighs a whopping 13.5oz with Crimson Trace laser grips. (Which mine has, the pic below is old...before I bought the CT's).
6) Without the hammer (431PD has exposed hammer, 432PD does not) it's ideal for snag free concealment.