If you want a gun to shoot heavy magnum loads, look for a Model 27 or Model 28. Both can be had in 4" and 6" barrels. The M27 also had the 3.5", 5" and 8 3/8" barrel lengths but these are somewhat hard to find. These are built on the same N-Frame S&W uses for the .41/.44 Magnums. Unless you're shooting hot magnums all the time, these are hard to wear out.
A Model 686/586 .357 is the intermediate L-Frame and popular with a lot of shooters since it is sizeable enough to absorb the recoil but smaller than the N-Frame. These guns will withstand a lot of magnum loads better than the K-frame.
In the K-Frame, S&W has offered a wide selection of guns. The fixed sight Model 13/M-65 are twins and rock sturdy guns. The Model 19 and Model 66 (stainless) are twins with adjustable sights and were, for many years, the police gun of choice. Accurate, sturdy and easy to carry. While these will stand up to magnum shooting, constant magnum use will wear these guns out faster than the others. The K-Frame is derived from the older M&P frame for the .38 S&W (short Colt) and older black powder cartridges. It was beefed up over the years and will serve decades if .38 specials are used for practice and magnums only for serious work.
S&W Now offers their 5-shot carry guns in .357. While these guns are typically known as J-frame sized, the newer guns are, as I've been told, designated I-Frame. These have been beefed up a little and some dimensional changes incorporated for the longer .357. I have a 649 "Bodyguard" model and while it will shoot .357's, they are not fun unless you really like recoil. Treat these like K-frames and they'll last for decades too.
If I could only have one it would, for me, be a choice between a 4" Model 19 or a 6" Model 27/28. The 19 could be carried comfortably but the N-Frame will handle anything the .357 round can put out. Not selecting the L-Frame is simply my own bias -- I've never liked the looks of a full underlug of the Colt Python or 686.
What about the new Scandium framed guns or Scandium/Titanium guns?
I'm not yet convinced that these guns will stand-up to heavy loads over time without developing problems. And to my eyes, the "Two Tone" look of the guns is not as appealing as a blued or stainless gun.