I have never been to cost co.I avoid Walmart like the plague simple because the employees don't give a shit about helping you (not that I blame them). I always hit up the locally owned grocery stores.
I hate everything about the Walmart experience actually. The other shoppers kind of freak me out. Everybody is in a bad mood, etc.
Edit: Also why does every Walmart have 40 check out lanes but only open 3? Why even build the others if your going to make me wait in line for another 30 minutes?