I have a GP-100 (4" Blue) and a 28-2 (6 in).
Both seem strong.
If I wanted to shoot tons of full bore 357 loads, I'd use the Ruger for the simple reason that if it broke, I could send it back to Ruger and they would have the parts to replace, of if not fixable could send me a new one. My 28-2 is nearly 40 years old.
Another option, although not an answer to the question you asked, would be my 627PC. It has a new N frame design, better support for the cylinder, and spare parts are available.
I suppose the strongest 357 magnum revolver would be a Redhawk as it's even stronger than the GP or N frame..
M627PC
