I buy mostly store brand products. What products do you have to have name brand on, that you won't skimp for store brand. Conversley, any store brands where you actually prefer the knockoff over the "real thing?"
I have to have name brand Cola. Prefer Coke, but Pepsi will do. Haven't found a store brand cola that's any good.
Boxed Mac and Cheese. Has to be Kraft. Perfect amount of cheese flavor. Anything else is too much cheese, or not enough.
HEB, a Texas supermarket chain, has their own line of salsa that is worlds better than any brand I've ever actually heard of.
Wegman's, Diet Wedge (Squirt knockoff), tastes better than the real thin.