Estwing is what is commonly used around here, and what I used when I worked in construction ~10 years ago. However it seems to me that the QC has gone down hill lately. I did not hear of problems frequently, but in the last year my brother has gone through two of the hammers, and has seen several other failures from those he works with. These are bent claws, split heads, and even broken handles. The Estwing warrenty has also been reduced. You used to be able to get direct replacements where you bought them, but now you have to send them back in.
I bought a high end wooden hammer for my brother the last time his Estwing failed and it didn't last a day before the handle broke. They take quite a pounding, and no wooden handle can take any impaction without failing shortly after. So it depends on what you are doing. For rough and heavy work you can break even the best ones quite quickly. I have been meaning to pick up a synthetic and see if that lasts any length of time. Hart and Deathstick are two of the wooden handled hammers with high reputations, Hart being generally held in better regard.
-Cliff