I've never purchased either H&K or Lorenzini RTW primarily due to fit--both are 24" wide through the chest (15" collar), which is simply too bulky for my frame. Fit aside, as noted by AlanC, Lorenzini uses superior fabrics for its eponymous label as well as RLPL. I also like the fact that Lorenzini/RLPL offers sport shirts in addition to dress shirts. Construction appears to be very similar, while H&K has a slightly more attractive spread collar. If buying at retail, H&K is a better deal, but when priced the same at discount, I tend to choose shirtings based on subtle patterns or colors (usually determined by fabric), and would, in all likelihood, bring home a Lorenzini.