I only have one revolver out of my collection. Mine is a 6" Stainless Steel Ruger GP 100 which is in .357 Mag. I originally bought it as a hunting backup but mostly use it as a range toy. The 6 inch barrel adds some extra weight which may or may not be a good thing depending on how you look at it. If you are going to lugging it around, it is heavier and you need a larger holster to carry it. If you intend on carrying it, I suggest you go with the 4 inch model. The extra barrel length and weight does help to tame recoil some. The extra sight radius also helps improve aim if you wanted to use it as a hunting gun. I would go with stainless if you are going to carry it since it will hold up much better to sweat and humidity.
The S&W 686 is also a very popular choice, but I like the beefiness of the GP 100.
This is the stock photo from Ruger's website. My grips have the wood insert in them and I like that look a lot better.