Single and inexpensive copper for best bang for buck. Better metal for better life. Never go with multi-prong. Its all marketing and there are no proven gains. After all a flame front is a flame front. And there is this thing call physics that the marketing guys seem to ignore
I prefer copper (best conductor of electricity for the engine environment) NKGs. I will never use BOSCH plugs. They blow out too often. I also went a couple steps colder.