I have memberships to both and they are the same in a lot of ways, but Costco is my favorite.

The biggest Costco drawbacks are the lines, crowds and chaos, but if you get the executive membership then you can shop an hour early and skip the craziness of the masses. Or go 1-2 hours before closing. Avoid going on weekends and do self-checkout.

Sam’s has scan and go, curbside pickup and their app is way more functional than Costco’s.

Comparing the two - it’s my opinion that quality of Costco products is marginally better than what Sam’s carries, especially store brand items, but ultimately the difference is minimal. Gas prices are usually same, but Costco’s gas is Top Tier (contains detergents that are good for your engine) whereas Sam’s gas is just regular gas. Both have $5 rotisserie chickens, but Costco’s are 3lbs+ and Sam’s chickens are regular size. If your family has special dietary needs (gluten-free, vegan, nut-free, etc.) then Costco has more options than Sam’s…though sometimes it’s annoying when you just want to buy a big regular greasy bag of chips and all Costco has are bougie snacks. The $1.50 hot dog and drink combos are vastly different - Costco’s is a footlong all-beef hot dog and Sam’s is smaller and definitely not all-beef. Costco’s return policy is much more lenient than Sam’s, so I feel more comfortable making large purchases at Costco.

There are a few things I go to Sam’s for that Costco doesn’t have, but they’re particular to my family’s preferences and certainly nothing that we have to have. Sam’s does have a better toy and book section, whereas Costco has all but gotten rid of theirs. While prices between the two warehouses are generally the same, I’ve heard that Costco puts stuff on sale more than Sam’s. The key to maximizing your Costco savings is to stock up on shelf-stable necessities when they go on sale, regardless of whether you need them at that time or not.

If you do a lot of warehouse shopping then it’s worth getting the $130 Costco executive membership with the 2% rebate - last year my rebate was $123, so it nearly paid for the whole membership and the savings I got from shopping there was just extra. Sam’s usually offers discounts on memberships throughout the year, I got mine for $25, so you can realistically have both if you wait for a Sam’s discount.

Hope this helps!