Originally Posted by headloss

Longevity, bearing grade, sealing, and in some cases, rebuild-ability. I suspect that a Phil Wood or SKF BB would long outlast other cartridge style square taper BBs, given the same use. Hard to say with any certainly since no objective 3rd party tests exist to my knowledge.

One of the reasons that I like outboard bottom bracket cups is that you can just replace the bearings when necessary without buying an entire assembly, which is why I'm not really looking back to square taper, ISIS, or Octalink with any fondness. The only exception is if I can't find a crank that I like which works with outboard style bearing cups (some of the Sugino touring cranks, for example, which are square taper only).