A few years ago a pal and I had a debate about wine buying. It was supermarket (with their buying in bulk power) against LWS (with the ability to source small numbers of tasty wines from different places.
To settle the debate we each bought half a dozen bottles, with a set budget. Six from supermarket, six from LWS, and all red. We then had friends round and did a blind tasting with everyone scoring each wine. Result was that the LWS beat the supermarket by a mile.
Also, our LWS knows what we like and gives great service. No contest really.