Well I'll ask since no one has yet. WHAT are you going to use the gun for? That will determine caliber, size/weight, and even finish.
Plinking: 22LR. Ruger MK2. Shoot all day for pennies. I shoot grouse with it.
Self defense against people: can't go wrong with a 9mm. Ammo has gotten good enough to stop anyone and everyone. No need for a slow and fat 45 or short and weak 40, though those will work fine too, but at reduced capacity. 9mm ammo is also fairly cheap comparatively. My personal choice: S&W M&P 9mm. Check out
pistol-training.com » Blog Archive » M&P Endurance Test Ends That's 62,000 rounds without a stoppage.
Dangerous animals defense: 10mm is what I carry, has the power of a 357 revolver, but in semi auto with 15 rounds in the magazine and is fairly light and compact even in full size. A revolver is the standard though as it won't jam and can be much more powerful, but at the cost of reduced capacity (5-7 rounds) and are much heavier and larger. There are backpacker models with stubby barrels and in lightweight materials, but it's not something you'd want to take to the range. Shooting a powerful, but light firearm is VERY unpleasant.
Hunting: Well there are many different hunting revolvers out there. I've only had experience with the S&W460 target shooting. Sweet shooting and well balanced.
Best of luck, learn how to shoot and how to do it safely. Go to a reputable gun store and pull up a chair. Check out your local range and shooting organizations.