I'll side with the majority here. The 442/642 is ideal.
Scandium frames are nice and are stronger than aluminum frames, so if longevity over thousands of rounds is important, get one.
I am not a fan of .357 Magnums out of scandium J frames. I have been firearms enthusiast since age 12 and they are the most unpleasant handgun I have ever fired. My .454 Casull revolver was nowhere near as brutal, nor was the .500 S&W Magnum I fired. If one is wedded to the Magnum chambering, a Colt Lawman or a M-19/66 with a 2.5 inch barrel is a better choice.
Many tout that the extra power is necessary when the time comes and more stopping power is good, BUT... a defensive firearm requires lots of practice and qualifications. The J frame Magnums are flinch inducing machines. I am against practicing with light loads and then carrying Magnum rounds based on experiences I saw on the range with cops who did this in duty revolvers back in the early 1980s.
A .38 Special +P round with a modern bullet design, combined with good placement, should do the trick.