Spark Plugs???

I have tried the NGK Plugs, the Bosch +4s, and I get the best mileage from the autolite plugs. Does this make any sense to anyone here. I thought those sucked and bought locally until I could order some. Since I ordered I noticed a loss in mileage after I replaced. I finally reinstalled and recovered my mileage. Has anyone else had this scenario happen to them? Thanks.

Some have very strong opinions about particular brands and types of spark plugs. In my own case, I get good mileage (47 highway) with el cheapo Autolite plugs so I don't see a need to try anything different. 320K miles and still going...