My very first gun, that started all this "gotta have that" madness, was a 627PC.
Since the purpose was home defense, with occasional target shooting for training and proficiency, the 5" fit the bill, and I liked the idea of 8 shots.
I chose the 627PC because I liked the balance and trigger. The underlug is kinda odd, but i grew to accept it. I think it helped to keep it from being too front heavy, and I am sure it was cheaper for S&W to build LOL.
Yes, it was expensive, but I am of the "buy once, cry once" mentality. HA if i had only known then what this would lead to, it was definitely NOT buy once! I now have a number of 357s', S&W K,L and N frames, and a couple Rugers, too.
I find that the ones i routinely pull out of the rack for range time are the original 627PC and the 19-4. That 19-4 has the sweetest trigger, even better than the PC. Thousands of rounds helps that, i suppose. I have a 19-3 i like a lot too, but that trigger on the -4 is just so sweet...
For 357 ammo, i only keep 158gn on the shelf, so I don't have to worry about the K frames. I don't see much difference between the 125 and 158 in recoil and noise, anyway, but that's just me.
I always say that there is NOTHING like a double action revolver to keep your trigger pull honest. I almost always start my range sessions with a revolver before proceeding to the semi-autos.
You already have about the finest revolver S&W made in the K frame, IMO, so you don't really need another one if you choose the right ammo. But if i had to make a recommendation, it would be among these:
S&W 19, 66, 686, 627, Ruger Security Six or Blackhawk (if single action intrigues you). If you can find one, the convertible Blackhawk also comes with a 9mm cylinder just for fun, though i find i don't use it much.
Just the two cents from a woman who likes revolvers a little.