Always the Smith.
Not to heave a stick of dynamite in the discussion but what if you wanted to handload some "zippier" rounds? Would you still stick with the Smith? I got a Ruger so I could build some bomber loads. If it goes boom I didn't destroy my beautiful Smith.
My next gun will be a S&W 627. I think the 8-shot .357 from S&W is one of the most incredible products in their line and for my preferences it is the most attractive .357 on the market.
I own both. As GP100 owner though, I'm a bit concerned with Ruger parts. Go to Ruger's website, look up parts for GP100 and you get holsters. Also no ebay or amazon sources for Ruger parts. Good thing they are "built like tanks" because I'm seeing that finding parts may be a problem. I can find parts for the "Security" series revolvers but virtually nothing for GP's and SP's.