For stuff like hops & general cooking, I use a Terraillon Model 907 we liberated from my uncle's house after he passed away in '97. I don't know how long it worked for him, but it's been working flawlessly since, with maybe 2 sets of new batteries. Sure hope it never goes out.
As has been mentioned in this thread, for these types of scales, the load cell is designed to handle maybe 7-11 pounds. Don't even think about putting anything way above the spec on there, because you can destroy the load cell = new scale.
For heavy stuff, I just use our digital bathroom scale, which is quite accurate. Grain bill = in bucket, then weigh (or already know) the bucket to arrive at the tare, then subtract. Also handy for weighing propane canisters so you don't have flameout 30 minutes into a boil with no spare. I use about 2 lbs for a 5 gal. brew session (I preheat some water indoors, because propane is cheaper that way), and as long as I'm aware of my tare weight (standard 20 lb. propane cylinders typically run 16.5 - 17.5 lbs, the tare weight is stamped on the handle) it's simple.