As a generalization I think you will get usually the best prices if you buy store brands. I buy store brands for many products and it saves us quite a bit of money. For some things like over the counter medicines I think the store brand is a automatic good deal. However some items I'm basically 'brand neutral' but I lean towards buying brand names as I feel theres lower quality in store brands. There are also a few brands that I won't budge on and I'll only buy the brand I like.
Store Brands Items that I definitely buy
There are some things that I automatically look for the store brand and am happy to get a store brand if its cheaper. For these things I don't really care who makes it and I consider all brands equally equivalent.
Over the Counter Medicines - ibuprofen (Advil), acetaminophen (Tylenol), cough syrup, etc.
Condiments - ketchup, mustard, etc.
Staples - flour, sugar, salt
Kitchen consumables - aluminum foil, paper bags
For all of these items I feel we don't give up any quality by buying a store brand and the prices are lower than brands.
Things I'm Brand Neutral on
For these items I don't exactly look for store brands but I'm not tied to a given brand. I usually just grab the cheapest item on the shelf. But I might pick a brand name rather than a store brand more often than not as I assume generally that the brands are 'better' product.
toothpaste
shampoo & conditioner
potato chips
toilet paper
popcorn
peanut butter
bread
pickles
For these items I'm not opposed to store brands but I'm either not sure the store brand is as good or I haven't found store brands that offer good savings for equal quality.
Brands I won't change
For the following items I won't buy anything but the brand in question. These are just brands that I personally like and have never found good replacements for.
Oreo cookies
Pepsi
Satin floss
For these items I simply can't find any other brands or store brands that are equal in quality.
What brands are you flexible on and what brands are you loyal to?