I would suggest the 357 Mag. over the others. As they have suggested here the fact you can Shoot 357 Mag *Full Blown Defense Loads which are more than adequate for defense. But also, you can shoot 38, 38+P 38+p+ and 38 Target Loads or Wad Cutters which are easy to find and as reasonable as ammunition today can be. If you are going to also carry it for CCW the 4" will be OK for both Range and CCW. But if you will only be using it for range target use, you might want to look at a 6" barrel. The Model 19, Model 66 or 686 Smith and Wesson is a good choice as well as other manufacturers make a good revolver. If you buy a used one be sure the cylinders lock up tight and correctly on each chamber of the cylinder.
You do that by holding the weapon in the normal grip. Cock the Hammer. Using your grip hand thumb to let the hammer down easily while pulling the trigger and holding the trigger to the rear. With the Hammer completely down. Check each chamber and cylinder one at a time to make sure each cylinder locks up tightly and doesn't have free travel from side to side. Also look at the lock locations (notches) on the outside of the Cylinder to be sure they do not look worn or damaged. A pistol not timed correctly will show wear or damage in that area. In addition look at the Barrel area where it comes through the frame facing the Cylinder if there is splattered lead or debris around the outside of the barrel (forcing cone area) and be sure to check on top of the barrel. Use caution! This is a sign of a pistol out of time/ poor lock up. Best to take someone with you that knows about pistols if buying a used one or find a reputable dealer that you know.
Most used pistols have not been fired that much as a rule.