For as long as I have been working on cars for some 15 years, not professionally, Auto Lite spark plugs have been the aftermarket Ford plug. NGK are for Japanese vehicles , and General Motors used ? I forgot, cause I never had a chevy. I have had or worked on a few fords, and had the misfortune of Japanese cars, and am looking forward to a General Motors soon.
I use the champion plugs because they were recommended by the factory and I am assuming they are the aftermarket or standard Jeep/Chrysler plugs. When and/or if I upgrade my ignition system I will use the better plugs which I do not know what they are cause I have yet to modify it.
Whenever I crossed this line I had problems with the plugs.
I have to stick with this because I learned it through trial and error.