I have owned a fair number of S&W .357 revolvers. These are the three I love the most:
1) 3.5" Model 27
2) 4" Model 586/686 (they shoot the same, but the blue 586 is SOO much prettier).
3) 2.5" Model 19/66 (same as above, the blue 19 is so much prettier).
As long as they are pre-1997, I don't care about dash number; the quality of the individual gun matters more. To me each of the above represents the best virtue of it's frame size and barrel length. I value guns that balance well, shoot well, and carry easily, so that's why I choose the above. Others may have different barrel lengths they like, but I've owned and tried multiple lengths in each frame, and these are the ones I'd keep above all others.