Most of my dress shirts come from A Man Hing Cheong. Excellent stuff overall, not cheap, but cheaper than equivalent quality off the rack in the US or UK, and a perfect fit, of course. I also have some from Ascot Chang, which is really famous, but I found not as good, in either service or in quality of the finished product.

In terms of durability, I found that a few of my A Man Hing Cheong shirts eventually shrink after repeated washings (we're talking years of use) with no fraying or wear, while all of my Ascot Chang shirts have suffered from this.