The best advice I can give is use a plug your engine likes and runs well on. Take the advice you'll get from the guys here and run with it. Try different plugs until you find one that fits your engine/prop/fuel combo and your flying style.

All that being said, I LOVE the McCoy plugs. Either the RC9 or 59 are great!
One is for high nitro and one is for low nitro and I never can remamber which it is without looking. []

Dr.1