G Shock, I've been wearing the same one for the last 8 years. It has taken all kinds of hits and nothing has happened to it, it's also still on the same battery!
I think it was FHM or Stuff magazine that did a durability test on sport type watches. They froze, boiled, dropped... you name it to each watch, they finally killed the G Shock after hitting it with a hammer 15 times.