The question "What is it for?" begs to be asked. The second question is do you handload?
If the gun is to be used for handgun hunting where that is legal, use the biggest you can shoot well. If the gun is to be carried for defense against dangerous animals as is legal in Canada with an ATC, the gun should be small enough to carry all day without it being a bother while you are working, but should not be so powerful that you cannot fire repeat shots quickly. Conversely it should be powerful enough to produce a large wound cavity and to penetrate deeply. My rule of thumb is the heaviest bullet a cartridge can drive at 1200 fps and I consider the .357 Magnum as the practical minimum. The practical maximum is the limitations of the individual shooter, but I would think the .475 Linebaugh would be close for even the most recoil hardened shooter.
If the gun is to be used solely on the target range, practical considerations barely enter the equation provided you are not engaged in a competition which mandates a type of gun and provided your range does not have a maximum caliber ceiling.
If you are going to shoot a centerfire handgun enough to become proficient, the financial burden is lessened with handloading. The bigger the cartridge, the bigger the saving. Aside from the cost saving, the handloader can produce ammunition that is simply not available from the factory. Although less important to the casual target shooter, this is a huge advantage to those who carry the handgun for hunting or defensive work.
The best quality guns IMHO are S&W and Ruger. Both companies make high quality guns, neither of which require the gun to be sent to a gunsmith to be made useful. What a good pistol-smith can do however is turn a very good gun into a personal masterpiece, with special attention to trigger pull weight, trigger break, and better accuracy with uniformed chamber throats, line boreing, and a Taylor throat, better, more rugged sights, custom grips and grip frames, the possibilities are limitless.
