I run std NGK V-Groove in my 2GS4, they run good, idles like a rock. Great power, but the 2GS4 has plenty of power....
Iridium is a good solid long lasting plug, but they are a bit more expensive than the V-Groove, but in the long run you would save $ using the v-groove.
As for power increase, no dyno test I have ever seen has shown SIGNIFICANT increase/decrease in power from a NEW plug to NEW plug no matter what kind it is. I have seen several over the years.
Fine wire plugs concentrate a higher amount of energy on the tip, which helps arc the gap in a high compression (or high boost) environment over a std plug. Technically you can run a wider gap with an Iridium over a std plug and still have sufficient arc on the gap.
I avoid platinum plugs, they often run hotter than the iridiums or std copper plugs. So that extra heat could (could, hard to prove, but commonly believed) induce pinging. Mainly in boosted applications people avoid platinum like ebola....