plugs???????????

Every mopar engine ive ever had,seemed to run better on a different plug type.For instance,my mild 318 in my truck prefers bosch platinums.I figured this out by trying different plug types,and temp ranges,until it ran the best 1/8th miles times,AND performed the best as far as milage,cold starts,etc.Now my last slant six,liked champion plugs the best,the bosch plugs never seemed to run just right in it,especially when cold.Its more a trial and error thing to get just the right plugs,even though i,like a lot of car guys have certain brands i like the best and try to use.