Basically, I'll try anything once if it's cheaper and then decide if I need to stay with the brand name or the generic
I buy JIF peanut butter because there is a big difference from the generic. Also, I use Cascade dishwasher detergent
Most store brands are made by a big name company. Food Lion American cheese singles are made by Land o' Lakes. Giant label chicken comes from Purdue and someone else (I don't remember who) uses Tyson
I had a neighbor who all the kids in the neighborhood said she made the best Mac & Cheese. Her secret: buy the generic and toss in a slice of American cheese (generic of course). My kids like Food Lion brand better than Kraft anyway.
Surprisingly enough, my husband prefers WalMart brand soda (@$.58 ea.) over Pepsi. He'd rather drink Coke, but for half the price, Walmart it good enough.
Brand name cereals are better, but generics are a LOT cheaper, so I buy generic kid cereals (too bad they'll just have to get used to the cheap stuff) and name brand adult cereal.
Generic pop-tarts suck, but the kids don't care and I'm not the one eating them. Quaker has a new one out that anyone who likes pop-tarts should try, they are MUCH better than "Pop-Tart" brand and they are higher in nutrition but my 4-yr old won't eat them b/c they don't have sprinkles (then he can eat store brand, they're cheaper anyway)
I usually use name brand laundry detergent but I've been experimenting with different kinds. I tried generic this last time and I'm going back to the good stuff.