Go for the specifications. Presently most of the manufacturers of vehicle recommend normal spark plugs.
I used Denso iridium plugs on IO pajero, it lasted only 10,000 km.
Then I thought it must be duplicate and get down plugs from Denso iridium plugs for RAV4, from Singapore, it lasted only 12,000km
Earlier engines are manufactured with timing chain and later changed to belt and now reversed back to timing chain.
Originally copper plugs are used for over 100 years and now again most Japanese and European manufacturers using copper plugs
