I can tell you about an article that tested platinum tipped plugs, and some that lost their tip and were sitting on top of the piston, and bouncing around like a little marble.
The iridium plugs are suppose to be the best, I use NGK, but they aren`t cheap, depends on what you can afford. Like all systems that rely on several components it is not one component but a series that ensures the best result, eg leads, you can have great plugs but inferior leads will still retard spark. That is why I bought Magnecore racing leads to go with the iridium plugs.
Again this is one of the key elements to performance, the biggest meanest mother of a motor can`t perform to its potential without strong consistent spark, why skimp on a few bucks.