Professional mechanics are pretty loyal to specific hammers. They usually have multiple hammers in their arsenal--different weights, different length handles, different head designs, different handle composition--but there's always one they use most often.
My friend Mark favors a 24-oz, solid-steel, ball peen head on a hickory-wood handle. My favorite is a 24-oz shot-loaded ball peen head on a polyurethane handle with a steel shank. Mark says a wooden handle absorbs some of the blow and is more comfortable to swing. I say I break wooden handles too easily, can feel the shock-absorbing benefits of the lead shot shifting in the cavity inside my hammer's head, and have never broken my polyurethane/steel shank handle.
You probably think we're a little nuts, being so fussy about hammers, but admit it: there's one hammer in your toolbox you prefer to grab when it's time to beat on something. Maybe you like the weight, or the balance of the head, or the length of the handle. Whatever the reason, make mental note of the size and style of your preferred hammer, so you can replace it with an exact replica if you lose it.
Because if you lose a favorite hammer and replace it with anything less than an exact duplicate, you'll think about the lost hammer every time you go to pound on something.