My two cents are this: what is the situation you're going to be using the gun in ( carry, bedside, etc) , and what are you comfortable with? Personally I have a used Smith and Wesson Model 36 .38 Special that I got for cheap at my LGS. It shoves in my cargo pocket, I can carry it everywhere, and .38 has a proven track record and low recoil fitting such a small gun, not even mentioning the sheer reliability of the revolver mechanism itself.
As for bedside/ home defense, you have the advantage of not carrying it everywhere like a CCW gun. Use what you're comfortable with. Personally that's my old SKS I got at a Black Friday Sale. Always look for deals and ways to squeeze the most value out of the system.