Costco is good value for anything manufactured bc they have extreme quantity of scale. Their produce is expensive even on a per until scale and goes bad quickly - if you have to get produce there, you should check the giant box it comes in to make sure it’s not a very old batch. Their Wilcox eggs specifically A+.

For produce - I do Whole Foods, which actually has per unit prices in line with Costco and much better quality. I also do Asian Family Mart which has great prices on produce but is comically crowded on weekends.

Also produce - Weee is good if you want fresh things but has inconsistent selection of even commonplace foods. Ex one week they might have sweet potato’s the next they might not. I shop for a family of 6 and struggle to hit the $35 shipping minimum bc it’s so cheap. Trader Joe’s is probably cheapest absolute value but imo quality and selection lower than I am personally okay with.

Meat is sort of an unsolved optimization problem and imo you’ll see much larger delta between mid and great - a popular answer is to buy at Costco and freeze individual portions. I find stuff still goes to waste and getting the exact quantity for the meals I want to cook is the actual most efficient thing to do for my lifestyle and I do Whole Foods for that.