GP-100
Kind of a wide range for a question, since the price and type of gun varies so widely, but for general purpose field use, not just self defense, I don't see how an autoloader can compare with a revolver.
Snakes, squirrels, rabbits, birds, coyotes, deer, even bears, can all be taken with the right ammo, as well as defense against two-legged predators, and it's unlikely ever to jam.
Since you're going to be carrying the gun while hiking, I'd suggest a short underlug model to save a little weight, but Ruger doesn't make them anymore, though you can find them used. I'd definitely consider the 3 1/16" SP-101 if you want to save quite a bit of weight (36 vs. 27 oz empty).
In other revolver options there is also the S&W Model 60 which is only a little more expensive, has adjustable sights, and weighs 24 oz. On the low end, for a gun that might well get scratched abused, you could go with a Taurus or Rossi.
Overall, I think the SP-101 would be an even better choice that the GP-100 for most uses.