I prefer semi-autos for carry, but small revolvers are a great choice for BUG duty (great for pocket or ankle carry). I have owned a couple S&W 642's and I currently own a S&W 360 PD and a Ruger SP 101. All snubbies (2 inch or so barrels). Here is my take.
Carry - I love my SP 101, but there is a noticeable size / bulk difference for me compared to the S&W J frames. The SP 101 can be pocket carried OK, but the J frames absolutely disappear in my pocket. The SP 101 is also heavier. But that is a big positive when it comes time for the range (see below). The J frames win here.
Shooting - Shooting .357's is a painful experience (for me) with a J frame. Extremely painful if it's my Scandium framed 360 PD. But with the SP 101 it is completely tolerable. Not pleasant, but very tolerable. Shooting 357 Mags in my SP 101 is about the same as shooting 38 Specials in my 360 PD. By extension, shooting 38 Specials in the SP 101 is an absolute joy. Five rounds rapid fire and the sights don't even move off target. A lot of fun. Overall, the SP 101 wins in this area.
Accuracy / Trigger - I have not noticed much difference in accuracy. These are definitely short range guns. 5 - 10 yards. Not much more. Personally, I found the trigger on the SP 101 to be a bit gritty and rough. But the DIY trigger job and shim installation was pretty easy and made a huge difference. The trigger is now comparable to my S&W's. So I'll call this area a tie.