I believe in the suggestion that most of the legendary "stopping power" of the 125gr .357 comes from several factors:
1) At the time, these were probably the most reliable expanding bullets. Driven hard enough (1400-1500 fps) the bullets "behaved" nicely, expanding and penetrating when hollowpoints at lower speeds wouldn't expand.
2) It has been suggested (can't remember where to quote) that there were more experienced, practiced and "gun savvy" officers using the Magnums as an option, when a .38 or .38 +P may have been department issued. Better shot placement = better results. (I've also seen this as a possible reason why the .45 ACP is rated so highly, being more common with enthusiasts, rather than the rank-and-file.)
3) Psychology! A full-power .357 out of even a 5-6" barreled revolver is quite impressive from a shock-and-awe perspective.
As for good .357 loads, pick one you like. I like 140gr Hornady XTPs, 145gr Winchester SilverTips would be good as well, along with any number of other options.