Canon's EOS 1V would tip my list for the best weather sealing of camera body, but also the most enduring. Sealing breaks down over time from many cycles of exposure to heat, cold, humidity and dryness, and all cameras that are sealed will usually have replacements made at the time of a major service. My EOS1N has been through patently atrocious conditions since 1994 and has never been serviced. It is sealed along the prime control area and back cover. Remember that a camera is only as good as the lens on the front -- this is where the consideration of weather resistance should be and is more important, all things else being equal.