The COLT Python double-action triggers not only approach the S&W, they are arguably better. Some of the King Cobras are also quite good. Shop around andyou MIGHT find a Python in the $600 price range, but be prepared to look for a while.
S&W triggers, otherwise, are quite good, but a friend bought a Performance Center 625, recently, that was horrible. He was really perplexed.
I have no experience with the Ruger handguns, but know from firends who have them that they can be 'smithed quite easily. But that's true of nearly any revolver quality, however.
I think the Rugers *MIGHT* be more robust than the S&W with a full diet of +P or hot ammo.
The Security Six can be found quite inexpensively and are surprisingly good guns. But not exciting. The GP100 appears to be an excellent choice, but I'd look for a used one.