Having experience with a 120 pound rottweiler/doberman mix, I feel confident to say that strong gear is very important with a strong dog. From chewing to pulling, vigorous usage, and the elements outdoors, some gear just doesn't cut it.
Going on a walk and having a clasp break partial way through your adventure can be more than annoying. Nylon flat leads are easily chewed, and an unexpected "off-leash" walk could get you or Fido into a pickle. I have seen it happen on more than one occasion, with my dog and others' Houdini hounds. All it takes is 3 seconds peering through that camera lens or pair of binoculars, and chomp chomp your dog is loose.
I have found one brand of dog gear that has proven over many field tests to out stand most others. RUFF WEAR has many products for outward-based dog accessories. My favorite leash is similar to a mountain climbing rope with reflective material intertwined. The handle is quite comfortable as well, lined with a firm pad. The clip is made with a climbing style carabiner that locks.
I recommend this brand highly for large, strong active breeds. I have not been disappointed yet.