It really depends on what fits your hands the best...
Personally I would favor a S&W K frame in .357 mag ( like a model 19 or 66 ) in a 4" ....( and there are no frame issues if you're shooting a standard 158 gr bullet in a K frame S&W ). A J frame S&W to me ...is too small in my hands for me to manipulate it effectively.
Personally I find a snubbie ( 2 1/2" ) is difficult to shoot well beyond 21 feet or so ...especially quickly for double taps out of a holster.../ where the 4" in my hands ..is just more stable...and way more effective.
I also like the L or N frame ....357 mag's ( mod 686 or mod 27's ) but they're a little too big and heavy to carry ..even in a 4" ( and I'm a big guy )... lots of good choices.