637, then 442/642/etc...
I've got a 442 and 637, and have shot the new plasticy-laser .38 S&W Bodyguard quite a bit. I am with 1911gobang here - I am a huge fan of the 637.
I can shoot the bodyguard more accurately than either the 442 or 637 at 10-15 yards, without the laser. I've shocked myself with 5 round groups at 10 and 15 yards with... 4 or 5 holes touching. I can also shoot the bodyguard much more accurately with the laser at almost any range. BUT there are 5 reasons why I wouldn't buy, use or depend on one of the new S&W Bodyguard .38's. (unless every other pistol and revolver that I have was broken/stolen/etc)
1) Although the Bodyguard is much more accurate in slow, deliberate, aimed fire, I can point shoot into a paperplate from 7-10 yards all day with the 442and the 637, and although not the frankly amazing accuracy of the bodyguard 38, I am even more accurate with aimed fire where I acquire a sight picture, think for a bit and concentrate on marksmanship fundamentals. I'd say - at 7 yards, I can shoot minute of ping-pong ball on an exceptional day, and minute of baseball on most days.
2) I cannot point shoot the S&W Bodyguard .38... it just aligns wrong for me. Groups are impossibly large, even at 7 yards.
3) The laser on the .38 bodyguard is a cheap piece of work. It is excessively complex to operate and for me, the silly cheap laser requires concentration and fine motor skills that might not be available in the sort of stressful situation where I am likely to NEED the revolver.
4) The cylinder release is unlike any other small revolver, anywhere. With every Colt, S&W, Taurus, and essentially every other double-action revolver I've ever seen, there is a small latch of some sort on the left hand side of the pistol that either pushes or pulls to open the cylinder. That latch can be opened with 1 thumb, and with the same hand that holds the pistol, so the other hand is free to reload. With every other revolver. To me, the 38 bodyguard requires 2 hands to open the cylinder, meaning reloading is an extra step, and is extra slow.
5) For me - the .38 bodyguard produces noticably more recoil than either the 637 or the 442. What kind of mystery polymer increases recoil? That just makes no sense to me... but it is how it felt.
Based on those things, and the mushy trigger, that I didnt get into, I just don't think the bodyguard is up to S&W's standards of quality. It feels like somebody at S&W said "hey, lets do a revolver in polymer that will cost about $400, with laser" and they just stuck something together without any regard for recoil, quality, reload, trigger, or any functional quality that a small concealable revolver requires to be effective as a small concealable revolver. (except accuracy)
If I wanted a gun to make the smallest possible group, I would be happy to shoot one. For anything else that I might want a small revolver for, the 637 is would be my choice 9 out of 10 times, and the 442 or any other variation (642, etc) would be next. After that, Id get a used Colt Detective Special off gunbroker. If that wasn't an option, I might get an LCR in either 38 or 357, further down the list, I might get a Taurus 856, or an older Taurus 85. If I couldnt do that, Id find a Charter Arms 38... LONG after I had exhausted every other option... I'd make due with a S&W 38 bodyguard. BUT - I'd never consider +P ammo, I'd train really hard with snap caps to figure out a way to reload, and I'd never ever use the laser.
Course, thats entirely my opinion. Opinions vary, and everybody's got one.