Like engine oil, everyone has there own preference for spark plugs. It's been my experience that in some instances, certain plugs work better in certain engines. In my Ford, I use Motorcraft/Autolites. GM cars seem to work best sticking with A/C Delco's. I haven't had a Chrysler product in a while, but I had no problems running Champions.

On foreign cars like my Suzuki, nothing beats NKG's. I've run these in my race car with no problems at all.

Like anything, having the right plug helps. Sometimes a bad experience with a certain brand of plug may come down to the wrong heat range for the car using them.