I have Motorcraft awsf-c12's in my car gapped at .054 and they work great. They are two steps colder than stock and copper. Copper is better in terms of performance since it is less resistant to electrical charge than platinum. However, you have to change coppers more often. I'de say just use coppers and change them out every year. As for which brand, I don't know if Autolite and Motorcraft are the same but I do know Fords come equipped with Motorcrafts and I know many guys using Autolites without problems. It should be noted the Autolite 764's are stock heat range. For better performance, might want to try 1 or 2 heat ranges colder than stock. Gap them at .054 for a n/a application.
yes the coppers are better. platnium plugs are only in there because they last 100k miles and ford doesnt have to deal with changing them under warrenty. on a car that is easy to do plugs on like a mustang (do a toyota camry v6 and u know what i mean by hard) just use coppers.
o btw autolite makes the motorcraft plugs. ford and autolite have a long history together. a lot of the carbs used on fords were autolite carbs. people think that the motorcraft oil filters are fram because autolite/prestone/fram are teh same company. motorcraft oil filters are wix/purolator depending on who they use that week.