Many years back I had an 86 Ranger 4x4 that ran happily for mebbe 125,000 miles on Autolite Platinums (after the first early change). In the meanwhile I changed out plug wires, rotors, dist caps. I had a little stumbling at low speeds, found a bad whire, was replaced under lifetime warranty, so I bought some more plugs while at it. I went with Bosche Platinums and was never quite happy. They just didn't seem to be right in this application, after mebbe 10,000 miles I reinstalled a set of Autolite (I believe double platinums) and ran another 50-60'000 miles before trading that truck in on another. My experience in THAT truck made me intend on using the Autolites.
I am planning on changing plugs soon in my Porsche, I'd not shy away from trying them again, am leaning to trying the newer Iridium plugs. My mech says stick with copper, I'm thinking trying something new.