There are many variations to pick from, but I would consider the following.
.38/.357 caliber. This will allow you to afford ammo, and having the gun in .357 will double its capabilities for you. Also, it will be a stronger firearm. You will be able to shoot .38 specials through it forever, and if you want to use it for a self defense weapon, you will not have to worry about +P ammo or even full house .357s.
4" barrel. To me this is the perfect length barrel for target practice, and possible home defense. While a bit large for CCW, it can be done, but you stated that it was primarily for target practice.
K or L Frame. The model 19 K-frame is revered by many here. I myself prefer the slightly larger L-Frame (model 686 for example.) The even larger model 28 (N-Frame) is a beautiful gun, but a bit large for some folks. All can be found with a 4" barrel.
Stainless steel, nickel plated, or blued finishes are a matter of personal preference. Other variables include, but are not limited to target sights, target triggers, grip designs, etc.
Finally, it is my personal opinion that you would be better off if you found a used gun that does not have the integral lock. I won't try to explain it here, just do a search on this forum.
WG840