Dish detergent- for hand-washing, I buy a name brand. I've found that the store brands don't work as well, and I have to use 2 or 3 times as much soap to get the same benefit of the name brand. We usually use Ajax or Palmolive, but that's because I can get it cheapest at Dollar Tree ($1 for 16oz or 20oz. If I find these brands or Dawn cheaper elsewhere, that's where I buy them.
Cereal- DH is somewhat picky. He'll do store brand "honey-nut cheerios" but his regular cheerios have to be Cheerios, and he only likes Kellogg's Raisin Bran. Also Shredded Wheat with Bran has to be the name brand, not store brand. He is OK with store brand (usually Hannaford) on most other cereals.
OJ- HAS to be not-from-concentrate.
Yogurt, sour cream, cream cheese- We don't buy any that has gelatins or thickeners added. Milk, enzyme, salt... obviously flavorings for the yogurt. That's about all I want in these products.
Laundry products- Usually buy All or Arm&Hammer, both unscented if possible. Occasionally I'll buy something cheaper (Sun? and there's something else..) but always regret it. For fabric softener I prefer Snuggle or Final Touch but will shop by price, too. I get dryer sheets at Dollar Tree, whatever's the best deal. For stain remover, all I use is Shout Gel. It's worth the price, to me!
Beer- only buy good beer. We have 3 microbreweries here in town, so we've gotten spoiled on the beer front. No more Bud, Miller, or Coors in this house!
Coffee- We aren't snobs about it, but we know what we like. I have to balance price against quality. We prefer Folgers Black Silk or Gourmet (also dark roast). I'll buy Maxwell House but only if the price difference is more than $1. Yes, there are more pricey brands we love (Green Mountain, for example, or local roasters) but this is where the price thing comes in. I often buy the more "upscale" coffees and we save them for weekend mornings when we are sitting around, savoring our coffee, instead of belting down a couple of "cups-o-joe" before heading out on our busy work days.
Peanut Butter- name brand, on sale. I think Peter Pan is our favorite but we like Skippy and Jif, too.
Saltines- I don't eat these, but they are DH's favorite snack food. HE LOVES Zesta, but most stores in New England don't carry them. If I am on a trip and find a store with Zesta, I'll bring them back as his "gift" from my trip! If not Zesta, it has to be Krispy. NOT PREMIUM!!!
Soup- Campbell's. DH will also eat Progressive, but I'm not a fan.
Most everything else is purchased by price or preference, meaning, for example, DH only likes unscented skin cream but doesn't care about the brand. I will use a variety of skin creams, soaps, etc., although I like to stock up on certain Bath&Body Works scents when they are on sale.