I was a Costco member for years, once I got married and had kids. When moving back in 2008 we had Sams. I was exited to hear Costco was coming to BCS. I figured there would be a lime miles long to get into Costco when they opened.
I decided to get my Costco membership a couple of months ago when I was in Cypress to avoid the lines.
When shopping at the Cypress Costco, I realized that Sam's had made a lot of strides over the years. The difference overall is minimal. A lot will have to do with the specific products you buy.
I think the prepared and cook & serve dishes at Costco are much better. I also like some of the other Costco branded food items a little better. I do not buy that kind of stuff a lot so the difference is minimal.
Costco uses top tier gas (Chevron I think) and that's a great value. Costco also has some great third party vendors for things for your home like flooring, windows, A/C units, generators... Also some deals for rental cars, event tickets, etc.
Costco's pricing is not as competitive as it used to be. They used to blow away everyone when it comes to core household products. I think Amazon has thrown a wrench in to the mix when it comes to that kind of stuff.
Sam's has Scan & Go. That is huge. Being able to skip the check-out line is a big deal to me, might not be to someone else.
Sam's optical at least in College Station, is great. I have never had an issue buying glasses there. Donna in the optical shop just makes sure everything is right before placing an order.
The pricing at each seems very similar. Each one carries very similar products which rotate. Each one may have a preferred brand on things like appliances, etc.
To me they are now very similar. Years ago, Costco was head and shoulders above Sam's. If the Costco gas station is out of the way or one you buy a lot of prepared or ready , or are very brand loyal, then its probably a coin toss.
Just my take. - - I say go with a friend to which ever store you do not have a membership and check it out first.