My car came new with NGK spark plugs in it, which have performed fine, but I'm wondering about others experience with these as compared to Bosch. I want to buy a set of plugs to keep on the shelf for backup, and I'm wondering what you guys with more experience like to use. I checked the forum, and this hasn't been addressed in a couple of years. Thanks.
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NGK for me too.
I've used both in the past.
Can't honestly report any difference.
Pat Downs put KGKs in mine when he built it, so I'm sticking with them.
I haven't had good experience with Japanese plugs; NGK's or Densos. Depending on your thread size I would recommend Bosch or Champion/Harley Davidson (re-branded Champions).
NGK here as well 
If your car has stock heads with stock 14mm spark plug threads, use Bosch.
If your heads have small motorcycle threads, use NGK, like I do.
This has served me well over the years.
