I've own them both........while I liked the 357, I LOVE the 44 Mag. No contest which I'll always use.....oh yeah, the SS Puma lever is a great sidekick for my SS Redhawk.
Keep in mind the 44 Mag is enough for anything you'll ever see in close quarters, comparatively speaking the 357 is a marginal cartridge for many species.
Ditto, also own both and would go with the .44mag.