Ketchup is the exact product that taught me price, not brand is what is important.
My dad worked at a cannery. They canned apricots, peaches, pears, tomatoes and made tomato juice and ketchup. They had only one recipe for ketchup, and it went into Heinz, Del Monte, S&W, Hunts, store brands, and the canneries own private label.
I would say about about 90% of what we buy is based on price. This week be bought RC Cola, last week Coke, the week before Pepsi because they were all on sale at
Walmart for even less than Sam's American Choice Cola.
My wife has a few brands she is loyal to, she will only eat Le Sueur canned peas......she doesn't like fresh or frozen peas. She only uses Bakers brand chocolate for baking. My daughter is a vegeterian, and she's only brand loyal because isn't a big fan of soy based foods, so she only buys Quorn brand vegeterian products which are soy free.
There are a few brands we avoid. Dasani Great Value, and Aquafina bottled water, they taste funny to us.
The one product I don't get why anyone would be brand loyal to, milk.