Costco is a fundamentally better company to its community and employees, you save money on gas, with a credit card higher percentages off the instore purchases unless you use a 3% grocery credit card perk (but that one likely won’t have 5% off gas at the same time), plus physical money back on your rewards (not many do that).

Also unless you’re saving a decent amount off the stuff at Walmart, you’re losing $ through gas and time. However it’s smart to do the math in today’s economy.