.357 Magnum revolvers will fire .38 Special in standard and plus P loads. .38 Special chambered revolvers can only handle that cartridge due to the 1/8" +/- shorter chamber. A .38 Special may be rated for standard or +P but verify before you buy. All the Taurus firearms are stated to be rated for +P with the Ultralite models in some dispute on that historically. I would use +P in that one for SD purposes but train with standard loads.
The .357 will be your most versatile chambering for the ability to train with .38 Special for economy and load up the Magnum rounds if you feel that you need it. .38 Special +P HP defense loads should be enough for any two legged animals that you may encounter.