A spark is a spark is a spark. Once the mixture is ignited the spark is out of the equation.
Even professional racers in all types of racing use standard copper plugs.
Different alloy plugs (Platinum, Yttrium, Irridium for instance) are used for longevity purposes so you can extend the service intervals. They may last X times longer, but they do not make 1 iota of extra power from the engine.
I do agree certain makes of plugs work better then others in specific applications. Like a Motorcraft (Autolite) in a Ford product for instance. Champion in a Mopar and so forth.
