The correct answer is: Champion RC12YC.
If you foul out the Champion "too quick" it is because Champion sets the industry standard for heat ranges and the rest try their best to duplicate it as close as they can, using their own idea of what a correct heat range SHOULD be.
In other words...DON'T USE ANY HEAT RANGE COMPARISON CHART EVER.
If you want to run NGK, ND, AC etc or whatever...look up YOUR application in that spark plug manufacturers catalog.
End of rant............for now.