Engine masters already did the episode comparing spark plugs. Short version: doesn't matter when it comes to power output.
Platniums run hotter, iridium are harder, copper are cheap and work. Outside of more complex systems like mazdas skyactiv and similar, there's no new tech in spark plugs the last 35+ years..
The extra heat of the platinum helps them avoid fouling and last longer between changes and their adoption was more to keep up with EPA fuel consumption targets for more miles.
