Grocery saving comparison

Saw this on TV, dont remember the exact numbers. It claims that shopping at walmart will save over $1000, target will save $569, rainbow will save $104, at cub foods will cost $130 more, blah blah. I feel that rainbow is cheaper than cub foods, even quality is better, but some disagree. But I feel target is more expensive than rainbow in a lot of ways, walmart is cheaper but with low quality. Costco has some nice stuff with good price. It's impossible to compare price for all, but I shop at different stores for good prices.